A Nhóm
A/B Test
Phương pháp kiểm tra thống kê bằng cách hiển thị ngẫu nhiên hai biến thể (giao diện, nội dung) để xem cái nào cải thiện KPI tốt hơn.
a11y
Tên viết tắt của Accessibility (chữ a, 11 chữ số và chữ y). Cách thiết kế để mọi người, kể cả người khuyết tật, đều có thể sử dụng Web.
AbortController
API trình duyệt để hủy các tác vụ bất đồng bộ như fetch. Dùng để dừng yêu cầu khi component bị unmount.
Above the Fold
Khu vực màn hình có thể nhìn thấy ngay mà không cần cuộn trang. Nơi đặt nội dung quan trọng nhất và nút kêu gọi hành động (CTA).
Accessibility Audit
Kiểm tra để phát hiện các vấn đề về khả năng tiếp cận của trang Web. Kết hợp các công cụ tự động như Lighthouse và kiểm tra thủ công.
Accessibility Statement
Trang công bố tình trạng hỗ trợ, mức độ tuân thủ và thông tin liên hệ về khả năng tiếp cận của trang Web. Nhiều khu vực đã coi đây là yêu cầu pháp lý.
Accessibility Tree
Cây được trình duyệt tạo ra từ DOM và chuyển cho các công nghệ hỗ trợ. Các thuộc tính ARIA được phản ánh tại đây.
ACID
Atomicity (Nguyên tử), Consistency (Nhất quán), Isolation (Cô lập), Durability (Bền vững). 4 đặc tính cơ bản của giao dịch trong DB quan hệ.
ACID Guarantee
Đảm bảo của DB giữ cho dữ liệu nhất quán ngay cả khi giao dịch thất bại giữa chừng, thông qua 4 đặc tính ACID.
Adaptive Loading
Chiến lược hiệu suất Web tự động điều chỉnh tài nguyên và tính năng dựa trên hiệu năng CPU, bộ nhớ và tốc độ mạng của thiết bị.
AES
Advanced Encryption Standard. Tiêu chuẩn mã hóa đối xứng hiện đại. AES-256 được khuyến nghị vì độ bảo mật và tốc độ tốt.
Affordance
Gợi ý thiết kế giúp người dùng hiểu cách tương tác một cách trực quan, ví dụ như hiệu ứng nổi của nút hoặc gạch chân liên kết.
AI Agent
Hệ thống dựa trên LLM tự động lập kế hoạch và thực hiện nhiệm vụ bằng cách sử dụng công cụ. Thường hoạt động theo mô hình ReAct.
AI Alignment
Lĩnh vực nghiên cứu đảm bảo mục tiêu, giá trị và hành động của hệ thống AI phù hợp với ý định của con người.
AI Safety
Lĩnh vực nghiên cứu đảm bảo hệ thống AI không gây hại ngoài ý muốn. Bao gồm tính có thể giải thích và tính mạnh mẽ.
Amazon Aurora
RDBMS quản lý hiệu suất cao của AWS, tương thích với MySQL/PostgreSQL. Tốc độ nhanh gấp 5 lần MySQL tiêu chuẩn.
Amazon RDS
Dịch vụ DB quan hệ quản lý của AWS, cung cấp MySQL, PostgreSQL, MariaDB, v.v.
Amazon S3
Dịch vụ lưu trữ đối tượng của AWS. Có khả năng mở rộng không giới hạn và độ bền cực cao (99.999999999%).
AMQP
Advanced Message Queuing Protocol. Giao thức truyền tin của các Message Broker như RabbitMQ.
Animation Performance
Phương pháp duy trì 60fps bằng cách chỉ sử dụng transform và opacity trong CSS để vẽ trên lớp GPU composite.
Ansible
Công cụ quản lý cấu hình và IaC không cần agent. Tự động hóa thiết lập máy chủ bằng Playbook YAML.
Apache Flink
Framework xử lý phân tán có khả năng xử lý luồng sự kiện lớn trong thời gian thực. Thường kết hợp với Kafka.
Apache Kafka
Nền tảng luồng sự kiện phân tán hiệu suất cao. Dùng để thu thập log, microservices hướng sự kiện, v.v.
Apache Spark
Framework tính toán phân tán xử lý dữ liệu lớn song song. Dùng cho xử lý batch và ML.
API
Application Programming Interface. Giao diện lập trình ứng dụng, quy định cách các phần mềm kết nối với nhau. Phổ biến nhất là REST API trao đổi JSON qua HTTP.
API Gateway
Cổng nhận yêu cầu từ client và điều phối đến các microservices. Đảm nhận cả xác thực và giới hạn lưu lượng.
API Key
Chuỗi token dùng để xác thực truy cập vào API. Việc quản lý quyền, xoay vòng và phạm vi là rất quan trọng.
API Mocking
Máy chủ trả về phản hồi giả thay vì backend thật trong quá trình phát triển. MSW là một công cụ tiêu biểu.
API Versioning
Chiến lược duy trì tính tương thích ngược của API khi thay đổi. Thực hiện qua đường dẫn URL, header hoặc query param.
App Router
Hệ thống routing dựa trên file từ Next.js 13+. Đặc trưng bởi cấu trúc layout lồng nhau sử dụng React Server Components.
ARIA
Quy chuẩn của W3C bổ sung vai trò, trạng thái và thuộc tính cho HTML dành cho trình đọc màn hình.
aria-live
Thuộc tính ARIA thông báo cho trình đọc màn hình về nội dung thay đổi động. polite là không ngắt lời, assertive là đọc ngay.
Aspect Ratio
Tỷ lệ khung hình. Sử dụng aspect-ratio trong CSS để duy trì tỷ lệ (như 16:9) trong layout responsive.
AST
Abstract Syntax Tree. Biểu diễn mã nguồn dưới dạng cấu trúc cây để các công cụ như Linter hay Babel phân tích.
Astro
Web framework mặc định không gửi JavaScript xuống trình duyệt. Sử dụng kiến trúc Islands để tạo ra các trang Web cực nhanh.
async/await
Syntax for writing async code in a synchronous style. The modern standard for Promise-based async in JS/TS.
Atomic CSS
CSS methodology where each class has a single styling responsibility. Tailwind CSS is the prime example.
Atomic Design
Phương pháp thiết kế UI chia thành 5 cấp độ: Atoms, Molecules, Organisms, Templates và Pages. Giúp tăng tính tái sử dụng và nhất quán.
Attack Surface
Tổng hợp tất cả các điểm mà kẻ tấn công có thể xâm nhập. Giảm số lượng endpoint API và cổng mở giúp thu hẹp bề mặt tấn công.
Attention Mechanism
Công nghệ cốt lõi của Transformer. Cơ chế tính toán trọng số liên quan giữa tất cả các token trong một chuỗi.
Auth Rate Limiting
Giới hạn số lần thử đăng nhập để ngăn chặn các cuộc tấn công brute force và credential stuffing.
Auto Scaling
Cơ chế tự động tăng giảm số lượng máy chủ theo tải trọng. Ví dụ: AWS Auto Scaling Group hoặc K8s HPA.
AutoML
Công nghệ tự động hóa việc lựa chọn mô hình, tìm kiếm siêu tham số và kỹ thuật đặc trưng trong học máy.
Autoprefixer
Plugin PostCSS tự động thêm tiền tố trình duyệt (vendor prefixes) vào CSS để đảm bảo tính tương thích.
Availability Zone
Các nhóm trung tâm dữ liệu bị cô lập về mặt vật lý trong đám mây (như AWS). Giúp đạt được tính khả dụng cao.
AWS Fargate
Engine chạy container serverless của AWS, không cần quản lý máy chủ. Thường dùng với ECS hoặc EKS.
AWS Lambda
Dịch vụ tính toán serverless của AWS chạy các hàm theo sự kiện. Trả tiền theo số lần thực thi.
AWS Step Functions
Dịch vụ điều phối luồng công việc serverless của AWS. Xây dựng các luồng nghiệp vụ phức tạp từ Lambda và các dịch vụ khác.
Adaptive Bitrate
Streaming technology that adjusts video quality in real-time based on network conditions.
Adversarial Attack
Technique that tricks AI models by introducing subtle, human-imperceptible noise into data.
Agentic UI
UI that autonomously adapts and generates components based on AI agent goals and user intent.
Anchor Positioning
Modern CSS feature allowing elements to be positioned relative to a specific 'anchor' element.
Anti-aliasing
Technique used to smooth out jagged edges in digital images and fonts.
ABI
Interface between two binary program modules, often between an OS and an application.
AI Artifacts
Unnatural errors or distortions produced by AI models during content generation.
Asymptotic Notation
Mathematical notation used to describe the limiting behavior of an algorithm's performance.
Atomic CSS-in-JS
CSS-in-JS approach generating single-purpose, atomic classes for maximum stylesheet reuse.
ABAC
Authorization model that grants access based on user, resource, and environmental attributes.
AR (Augmented Reality)
Technology that overlays digital information, such as images or sound, onto the real world.
Auto-regressive Model
AI model that predicts future values based on past values, fundamental to models like GPT.
API Subset
A portion of an API's total functionality, often exposed for limited use cases.
B Nhóm
B2B SaaS
Phần mềm như một dịch vụ dành cho doanh nghiệp. Thường yêu cầu hỗ trợ đa người dùng (multi-tenancy) và SSO.
Backpressure
Cơ chế kiểm soát luồng tin báo cho phía thượng nguồn chạy chậm lại khi phía hạ nguồn không xử lý kịp.
Backpropagation
Thuật toán lan truyền ngược lỗi để cập nhật trọng số cho các tầng trong mạng nơ-ron.
Barrel File
File index.ts dùng để xuất lại (re-export) nhiều module, giúp làm gọn đường dẫn import.
BASE
Basically Available, Soft state, Eventual consistency. Mô hình nhất quán thường dùng trong NoSQL, đối lập với ACID.
Base64
Mã hóa biểu diễn dữ liệu nhị phân bằng 64 ký tự ASCII. Dùng để nhúng ảnh Data URI, v.v. Lưu ý đây không phải là mật mã hóa.
Batch Normalization
Kỹ thuật chuẩn hóa các giá trị kích hoạt trong một mini-batch để làm ổn định và tăng tốc độ huấn luyện mạng nơ-ron sâu.
bcrypt
Thuật toán băm mật khẩu có hệ số chi phí để làm chậm các cuộc tấn công brute force. Được khuyến nghị dùng cho mật khẩu.
BEM
Block, Element, Modifier. Quy tắc đặt tên CSS giúp tránh xung đột style bằng cấu trúc block__element--modifier.
BERT
Mô hình Transformer hai chiều của Google dùng cho các tác vụ hiểu ngôn ngữ tự nhiên như phân loại văn bản.
BGP
Border Gateway Protocol. Giao thức trao đổi thông tin định tuyến giữa các hệ thống tự trị (AS) trên Internet.
BigQuery
Kho dữ liệu serverless của Google Cloud. Cho phép phân tích hàng petabyte dữ liệu bằng SQL trong thời gian thực.
Biome
Công cụ linter và formatter cực nhanh cho JS/TS viết bằng Rust, hướng tới thay thế ESLint và Prettier.
Blob Storage
Lưu trữ đối tượng cho dữ liệu không cấu trúc như ảnh và video. Ví dụ: AWS S3 hoặc Azure Blob Storage.
Bloom Filter
Cấu trúc dữ liệu xác suất giúp kiểm tra sự tồn tại của phần tử một cách nhanh chóng và tiết kiệm bộ nhớ.
Blue-Green Deployment
Chiến lược triển khai chạy song song hai môi trường, chuyển đổi lưu lượng để đạt thời gian chết bằng không.
Blur Placeholder
Kỹ thuật hiển thị ảnh mờ độ phân giải thấp trong khi chờ ảnh gốc tải xong. Có thể dùng blurDataURL trong Next.js.
Brand Guidelines
Bộ quy tắc về logo, màu sắc, font chữ để giữ tính nhất quán thương hiệu. Là nền tảng của hệ thống thiết kế.
Breakpoint
Ngưỡng chiều rộng màn hình trong CSS để thay đổi bố cục layout. Được định nghĩa bằng @media queries.
Browser DevTools
Công cụ gỡ lỗi tích hợp trong trình duyệt (Chrome, Firefox). Bao gồm các bảng Elements, Console, Network, v.v.
Brute Force Attack
Tấn công thử sai tất cả các trường hợp để bẻ khóa mật khẩu. Khắc phục bằng giới hạn số lần thử và khóa tài khoản.
Bug Bounty
Chương trình trả tiền cho các nhà nghiên cứu bảo mật khi họ phát hiện và báo cáo lỗ hổng một cách có trách nhiệm.
Build Tool
Tên gọi chung cho các công cụ chuyển đổi mã nguồn cho môi trường sản xuất (Vite, Webpack, esbuild, v.v.).
Bulkhead Pattern
Mô hình thiết kế khả năng phục hồi bằng cách cô lập các nhóm tài nguyên, ngăn chặn sự cố lan rộng ra toàn hệ thống.
Bun
All-in-one fast JavaScript runtime, package manager, and bundler.
Bundle Size Analysis
Việc trực quan hóa các thành phần trong bundle JS để tìm ra các thư viện không cần thiết hoặc bị trùng lặp.
Bundler (バンドラー)
Công cụ kết hợp nhiều module JS/CSS thành các file đã được tối ưu hóa. Webpack, Vite và Rollup là các ví dụ phổ biến.
B-Tree
Self-balancing tree data structure that maintains sorted data for efficient searches and inserts.
BFF
Design pattern where a dedicated backend is built specifically for a certain frontend interface.
Barrel Export
Technique of aggregating exports from multiple modules into a single index file for easier imports.
Bayesian Network
Probabilistic graphical model representing a set of variables and their conditional dependencies.
Beacon API
Web API for sending small amounts of data to a server without delaying the page unload process.
Behavioral Analytics
Method of analyzing user actions within an application to uncover patterns and improve UX.
BST
Tree data structure where each node has at most two children, sorted for efficient lookup.
Bitbucket
Git-based source code repository hosting service often used in enterprise environments.
Black Box Testing
Testing method that examines the functionality of an application without peering into its internal structures.
Block Scope
Region of code where a variable is accessible, limited by curly braces in languages like JS.
Blue-Green Deployment
Deployment strategy that utilizes two identical environments to ensure zero-downtime releases.
BLE
Wireless personal area network technology designed for low power consumption and short-range use.
B-Tree Index
Database index type using balanced trees to provide quick data retrieval for range and equality queries.
Buffer Overflow Protection
Security features that detect and prevent attacks exploiting memory buffer overflows.
BLL
Layer in an application architecture that manages core business rules and data calculations.
BOM (Byte Order Mark)
Character code at the start of a binary file indicating the byte order and encoding of the text.
C Nhóm
Cache (キャッシュ)
Cơ chế lưu trữ tạm thời dữ liệu đã lấy để tránh việc phải lấy lại lần sau. Là yếu tố then chốt để cải thiện hiệu suất.
Cache Busting
Thêm mã băm vào tên file để ép trình duyệt xóa bỏ cache cũ và tải file mới. Ví dụ: main.abc123.js.
Cache Strategy
Các mô hình đọc/ghi cache như Cache-Aside, Write-Through và Write-Behind. Lựa chọn tùy theo mục đích sử dụng.
Canary Release
Chiến lược triển khai phiên bản mới cho một nhóm nhỏ người dùng trước, sau đó mới mở rộng dần ra toàn bộ hệ thống.
Canvas API
API HTML5 dùng để vẽ đồ họa 2D trực tiếp trên trình duyệt bằng JS. Thường dùng cho game, biểu đồ và xử lý ảnh.
CAP Theorem
Định lý khẳng định hệ thống phân tán chỉ đảm bảo tối đa 2 trong 3 yếu tố: Nhất quán (C), Khả dụng (A), Chịu lỗi phân đoạn (P).
Card Sorting
Phương pháp nghiên cứu UX quan sát cách người dùng phân loại thông tin. Giúp ích cho thiết kế kiến trúc thông tin.
CDN
Mạng lưới các máy chủ phân tán giúp phân phối tài nguyên tĩnh nhanh chóng dựa trên vị trí của người dùng.
CDN Cache Invalidation
Thao tác xóa nội dung đã lưu trên CDN. Bước quan trọng để người dùng không thấy nội dung cũ sau khi deploy.
Certificate Pinning
Kỹ thuật cố định các chứng chỉ TLS cụ thể trong client để tăng khả năng chống lại các cuộc tấn công giả mạo (MITM).
Chain of Thought
Kỹ thuật yêu cầu LLM thực hiện suy luận từng bước, giúp tăng độ chính xác cho các vấn đề phức tạp.
Chunked Transfer Encoding
Mã hóa gửi phản hồi HTTP theo từng đoạn nhỏ. Dùng khi kích thước nội dung chưa được xác định ngay.
Chunking
Quá trình chia nhỏ tài liệu dài thành các mảnh phù hợp để đưa vào cửa sổ ngữ cảnh của LLM trong quy trình RAG.
Chunking (UX)
Phương pháp thiết kế UX chia nhỏ thông tin thành các nhóm để giảm tải nhận thức. Biểu mẫu nhiều bước là một ví dụ.
CI/CD
Continuous Integration / Continuous Deployment. Tự động hóa việc kiểm thử (CI) và triển khai (CD) mã nguồn một cách an toàn.
Circuit Breaker
Mô hình xử lý lỗi giúp phát hiện thất bại của dịch vụ bên ngoài và tạm thời chặn yêu cầu để tránh quá tải.
Circuit Breaker States
Máy trạng thái của Circuit Breaker gồm 3 trạng thái: Closed (bình thường), Open (ngắt kết nối) và Half-Open (thử nghiệm phục hồi).
clamp()
Hàm CSS nhận 3 giá trị: tối thiểu, lý tưởng và tối đa. Giúp tạo kích thước font chữ responsive mà không cần media queries.
CLI
Giao diện dòng lệnh. Người dùng điều khiển máy tính bằng cách gõ các lệnh văn bản trong terminal.
ClickHouse
Cơ sở dữ liệu OLAP hướng cột. Cực nhanh cho việc phân tích log và các truy vấn tổng hợp dữ liệu chuỗi thời gian.
Clickjacking
Cuộc tấn công chồng lấp các iframe vô hình để đánh lừa người dùng click vào. Ngăn chặn bằng header X-Frame-Options.
Client Component
Thành phần trong Next.js App Router được đánh dấu bằng 'use client', thực thi JavaScript trên trình duyệt.
CLIP
Mô hình OpenAI giúp khớp nối hình ảnh và văn bản trong cùng một không gian nhúng. Dùng cho tìm kiếm hình ảnh.
CLS
Cumulative Layout Shift. Chỉ số đo lường sự thay đổi bố cục bất ngờ trong quá trình tải trang. Một chỉ số Core Web Vitals.
CNAME
Loại bản ghi DNS ánh xạ một tên miền này sang một tên miền khác. Thường dùng cho CDN và tên miền tùy chỉnh.
CNN
Mạng nơ-ron tích chập. Chuyên dùng cho nhận dạng hình ảnh bằng cách sử dụng các lớp tích chập và pooling.
CockroachDB
Cơ sở dữ liệu SQL phân tán kết hợp tính co giãn ngang với tuân thủ ACID và hỗ trợ phân tán địa lý.
Code Injection
Danh mục tấn công rộng lớn nơi mã độc được tiêm vào ứng dụng. SQL Injection và XSS là các loại con của nó.
Code Splitting
Việc chia nhỏ bundle JS thành các phần nhỏ để chỉ tải khi cần, giúp giảm thời gian tải trang ban đầu.
Cognitive Load
Nỗ lực tinh thần cần thiết để hiểu và sử dụng giao diện. Thiết kế tốt là phải giảm thiểu tải nhận thức cho người dùng.
Cold Start
Độ trễ ban đầu khi một hàm serverless khởi động lại sau một thời gian không hoạt động. Đây là nhược điểm của serverless.
Color Blindness Accessibility
Thiết kế đảm bảo người mù màu có thể phân biệt thông tin bằng cách dùng hình dạng, icon bên cạnh màu sắc.
Color Scheme
Cơ chế CSS giúp chuyển chủ đề sáng/tối dựa trên cài đặt hệ điều hành thông qua media query prefers-color-scheme.
Column Store
Cơ sở dữ liệu lưu trữ dữ liệu theo từng cột. Rất nhanh cho truy vấn tổng hợp và lý tưởng cho khối lượng OLAP.
Composable
Hàm đóng gói logic có thể tái sử dụng trong Vue 3 (Composition API), tương đương Custom Hooks trong React.
Compound Component
Mô hình thiết kế React nơi thành phần cha và con chia sẻ trạng thái qua Context để tạo API linh hoạt.
Computed Property
Giá trị phản ứng được tính toán tự động và lưu vào bộ nhớ đệm từ dữ liệu khác. Cốt lõi của Vue và MobX.
Computer Vision
Lĩnh vực AI trích xuất thông tin từ hình ảnh/video. Bao gồm phát hiện vật thể và nhận dạng khuôn mặt.
Concurrent Mode
Chế độ trong React 18 cho phép tạm dừng và tiếp tục render để giữ UI phản hồi tốt khi xử lý tác vụ nặng.
Connection Pool
Cơ chế dùng lại kết nối DB để giảm chi phí thiết lập kết nối và quản lý xử lý đồng thời hiệu quả.
Connection String
Chuỗi định dạng URL chứa thông tin máy chủ, cổng và xác thực của DB. Quản lý qua biến môi trường.
Consistent Hashing
Thuật toán băm giúp giảm thiểu việc phân phối lại dữ liệu khi thêm hoặc xóa nút trong hệ thống phân tán.
Constitutional AI
Kỹ thuật định nghĩa nguyên tắc rõ ràng cho hành vi AI, cho phép mô hình tự cải thiện dựa trên các quy tắc đó.
Container Orchestration
Cơ chế tự động quản lý việc triển khai, mở rộng và kết nối mạng của các container. Kubernetes là tiêu chuẩn thực tế.
Container Query
Tính năng CSS áp dụng style dựa trên kích thước của container cha, giúp tạo các thành phần responsive độc lập.
Container Registry
Kho lưu trữ để bảo quản, quản lý và phân phối các Docker image. Các ví dụ phổ biến là DockerHub, ECR và GCR.
containerd
Runtime quản lý vòng đời của container bên trong Docker. Đây là runtime mặc định cho Kubernetes hiện nay.
Content Compression
Việc giảm kích thước truyền tải bằng cách nén các tài nguyên văn bản với Brotli hoặc gzip.
Content Negotiation
Cơ chế HTTP nơi client và server thỏa thuận định dạng phản hồi (JSON, XML, v.v.) qua Accept headers.
Content-First Design
Phương pháp định nghĩa cấu trúc nội dung trước khi thiết kế UI. Đánh giá thiết kế bằng nội dung thực tế.
Context API
Tính năng tích hợp của React để truyền dữ liệu xuống sâu trong cây thành phần mà không cần thông qua props.
Context Window
Số lượng token tối đa mà một LLM có thể xử lý cùng một lúc. Cửa sổ càng lớn thì xử lý ngữ cảnh càng tốt.
Contextual Inquiry
Phương pháp nghiên cứu thực địa bằng cách quan sát và phỏng vấn người dùng trong môi trường làm việc thực tế.
Continuous Delivery
Thực hành giữ cho mã nguồn luôn ở trạng thái có thể phát hành bất cứ lúc nào. Triển khai thường kích hoạt thủ công.
Contrast (コントラスト比)
Sự khác biệt về độ sáng giữa màu chữ và màu nền. WCAG khuyến nghị tỷ lệ 4.5:1 để đảm bảo khả năng tiếp cận.
Controlled Component
Mô hình React nơi các input được điều khiển bởi state và onChange, giúp đồng bộ hóa dữ liệu và UI.
Conventional Commits
Quy ước chuẩn hóa thông điệp commit bằng tiền tố như feat, fix. Giúp tự động hóa việc tạo phiên bản.
Conversion Rate
Tỷ lệ người truy cập hoàn thành mục tiêu cụ thể (như mua hàng). Chỉ số thành công chính trong UX.
CORS
Cross-Origin Resource Sharing. Cơ chế bảo mật của trình duyệt cho các cuộc gọi API từ các origin khác nhau.
CORS Preflight
Yêu cầu OPTIONS của trình duyệt gửi đi trước một cuộc gọi cross-origin để xác nhận quyền hạn từ máy chủ.
CORS Security
Thiết lập header CORS theo whitelist thay vì dùng ký tự đại diện để bảo vệ API khỏi các nguồn không xác định.
Cosine Similarity
Chỉ số đo lường sự tương đồng về hướng giữa hai vectơ. Dùng để so sánh độ gần gũi ngữ nghĩa giữa các vectơ nhúng.
Covering Index
Chỉ mục chứa tất cả các cột mà truy vấn cần, giúp tránh việc phải truy cập trực tiếp vào hàng của bảng chính.
CPU Profiling
Việc đo lường xem phần nào của chương trình tiêu tốn tài nguyên CPU nhất để xác định điểm nghẽn hiệu suất.
CQRS
Mô hình thiết kế tách biệt phần đọc (Query) và phần ghi (Command) để tăng khả năng mở rộng hệ thống.
Create React App
Công cụ tạo khung dự án React của Facebook. Hiện nay việc dùng Vite được khuyến nghị cho các dự án mới.
Credential Stuffing
Attack trying leaked email/password pairs on other services. MFA and password managers are the main defenses.
Critical CSS
Kỹ thuật trích xuất CSS cần thiết cho phần hiển thị đầu tiên và nhúng vào HTML để loại bỏ chặn render.
Cron
Bộ lập lịch công việc trong Unix. Tự động hóa tác vụ định kỳ bằng cách dùng các biểu thức thời gian.
CronJob (K8s)
Tài nguyên Kubernetes quản lý các batch job theo lịch trình, dùng cú pháp cron tương tự Unix.
Cross-Entropy Loss
Hàm mất mát đo lường sự sai khác giữa xác suất dự đoán và thực tế. Thường dùng trong phân loại.
CSAT
Customer Satisfaction Score. Chỉ số đo lường mức độ hài lòng của khách hàng đối với một tương tác cụ thể.
CSP
Header HTTP giúp ngăn chặn tấn công XSS bằng cách hạn chế nguồn script và việc thực thi script nội dòng.
CSR
Client-Side Rendering. JavaScript vẽ HTML trực tiếp trong trình duyệt. Là cốt lõi của SPA.
CSRF
Cuộc tấn công ép người dùng thực hiện các hành động không mong muốn từ một website khác.
CSS Animation
Tính năng CSS dùng @keyframes và animation để tạo chuyển động cho phần tử mà không cần JavaScript.
CSS Custom Property
Các biến CSS được định nghĩa với tiền tố -- (ví dụ --color) để có thể tái sử dụng các giá trị.
CSS Grid
Hệ thống bố cục 2 chiều của CSS. Cho phép định nghĩa hàng và cột để tạo ra các layout phức tạp.
CSS Mixin
Các khối style tái sử dụng được định nghĩa bằng @mixin và chèn vào bằng @include trong Sass/SCSS.
CSS Modules
Cơ chế giới hạn phạm vi của tên lớp CSS trong một thành phần bằng cách tạo tên lớp duy nhất lúc build.
CSS Subgrid
Tính năng CSS cho phép các phần tử con thừa hưởng hệ thống lưới của phần tử cha để căn chỉnh chính xác.
CSS-in-JS
Phương pháp viết CSS trực tiếp bên trong JavaScript. Emotion và styled-components là các ví dụ phổ biến.
CSV
Định dạng dữ liệu bảng phân tách bằng dấu phẩy. Được sử dụng rộng rãi để xuất/nhập dữ liệu giữa các hệ thống.
CTA
Nút hoặc liên kết thúc đẩy hành động của người dùng (như mua hàng). CTA ảnh hưởng lớn đến tỷ lệ chuyển đổi.
CVE
Hệ thống định danh duy nhất cho các lỗ hổng bảo mật đã được công bố rộng rãi (CVE-YYYY-NNNNN).
Cypress
Framework kiểm thử JS cho phép viết các bài test E2E trên trình duyệt với API trực quan.
Cache Eviction Policy
Algorithm defining which data to remove from a cache when it reaches its capacity limit.
Canary Deployment
Rollout strategy where a new version is released to a small subset of users before a full release.
Chaos Monkey
Tool that randomly terminates instances in a production environment to test system resilience.
Client Hints
Set of HTTP headers allowing a browser to provide information about the device and network to the server.
Cloud Agnostic
System design that avoids dependence on any single cloud provider's proprietary services.
Code Splitting
Optimization technique that splits code into smaller bundles to improve initial load performance.
Cold Standby
Redundancy strategy where a secondary system is available but powered down until a failure occurs.
Columnar Storage
Database storage format that stores data by columns rather than rows, ideal for analytical queries.
Composite Index
Database index consisting of multiple columns, optimizing queries that filter by more than one field.
Concurrency Control
Mechanisms used in databases and computing to ensure correct results when concurrent operations overlap.
CSP Level 3
Third level of the CSP standard, introducing features like 'strict-dynamic' for better security control.
Context-aware UI
UI that adapts its features and content based on the user's current environment and situation.
Control Plane
The part of a network that manages and controls where data traffic is directed.
Critical Rendering Path
Sequence of steps the browser takes to convert HTML, CSS, and JS into pixels on the screen.
Cross-functional Team
Group of people with different expertise working together toward a common goal or project.
CRUD
Acronym for the four basic functions of persistent storage: Create, Read, Update, and Delete.
Cyber Resilience
An entity's ability to continuously deliver its intended outcome despite adverse cyber events.
D Nhóm
DaemonSet
Tài nguyên Kubernetes đảm bảo mỗi Node chạy một bản sao của Pod. Dùng cho việc thu thập log hoặc giám sát.
DALL·E
Mô hình của OpenAI tạo hình ảnh chất lượng cao từ văn bản, dựa trên kiến trúc Diffusion Model.
Dark Mode
Chủ đề giao diện nền tối. Giúp giảm mỏi mắt và tiết kiệm pin trên các thiết bị màn hình OLED.
DAST
Kiểm thử bảo mật bằng cách quét ứng dụng đang chạy từ bên ngoài để tìm các lỗ hổng tiềm ẩn.
Data Augmentation
Kỹ thuật mở rộng dữ liệu huấn luyện bằng các phép biến đổi để tăng tính tổng quát hóa cho mô hình.
Data Fetching Patterns
Các chiến lược về thời điểm và địa điểm lấy dữ liệu (CSR, SSR, SSG, ISR). Cốt lõi trong Next.js.
Data Lake
Kiến trúc lưu trữ giữ dữ liệu thô ở định dạng gốc, phục vụ cho nhiều mục đích phân tích trong tương lai.
Data Masking
Việc thay thế dữ liệu nhạy cảm bằng dữ liệu giả để sử dụng an toàn trong môi trường phát triển.
Data URI
Định dạng nhúng trực tiếp dữ liệu (Base64) vào HTML/CSS, giúp giảm số lượng yêu cầu HTTP.
Data Warehouse
Kho lưu trữ tập trung dữ liệu có cấu trúc đã được tối ưu hóa cho phân tích. Ví dụ: BigQuery.
data-* Attribute
Thuộc tính HTML tùy chỉnh dùng để gắn siêu dữ liệu. Truy cập từ JS qua API dataset.
Database Cursor
Cơ chế con trỏ của DB để xử lý các tập kết quả lớn theo từng dòng mà không cần tải hết vào bộ nhớ.
Database Index
Cấu trúc dữ liệu giúp tăng tốc truy vấn trên các cột cụ thể. Có sự đánh đổi về hiệu suất khi ghi.
Database Sharding
Phương pháp chia nhỏ dữ liệu theo chiều ngang sang nhiều nút DB để mở rộng hệ thống.
DB Migration
Quản lý phiên bản các thay đổi lược đồ DB song song với mã nguồn qua các công cụ như Prisma.
DB Transaction
Cơ chế nhóm các thao tác SQL sao cho tất cả cùng thành công hoặc cùng thất bại, đảm bảo tính ACID.
DDD
Thiết kế hướng tên miền. Tập trung phần mềm xoay quanh nghiệp vụ cốt lõi bằng Entity và Value Object.
DDoS
Cuộc tấn công làm tràn ngập máy chủ bằng lưu lượng truy cập khổng lồ để làm tê liệt dịch vụ.
Dead Letter Queue
Hàng đợi lưu trữ các tin nhắn xử lý thất bại trong hệ thống message queue. Dùng để gỡ lỗi.
Debounce
Kỹ thuật chỉ thực hiện một hàm sau khi các sự kiện liên tiếp tạm dừng. Giúp tránh gọi API quá nhiều.
Declarative UI
Tư duy UI nơi bạn chỉ mô tả 'cái gì' hiển thị; framework sẽ xử lý cập nhật DOM. React dùng điều này.
Deep Link
URL cho phép mở trực tiếp một màn hình cụ thể trong ứng dụng. Dùng custom scheme hoặc Universal Links.
Defense in Depth
Tư duy bảo mật đa tầng, đảm bảo rằng nếu một lớp bị phá vỡ thì hệ thống vẫn được bảo vệ.
Deferred Loading
Kỹ thuật chỉ tải hình ảnh nằm ngoài màn hình khi cần thiết qua loading='lazy' hoặc Intersection Observer.
Deno
Runtime JS/TS được thiết kế lại bởi tác giả Node.js. Hỗ trợ TS trực tiếp và bảo mật mặc định.
Dependency Graph
Đồ thị có hướng biểu diễn phụ thuộc giữa các module. Dùng để tối ưu hóa việc đóng gói (bundle).
Dependency Scanning
Tự động kiểm tra các thư viện để tìm lỗ hổng bảo mật. Dependabot và Snyk là ví dụ phổ biến.
Deploy Preview
Môi trường chạy thử tạo tự động cho từng PR để xem trước thay đổi. Vercel cung cấp tính năng này.
Deployment Strategy
Các phương pháp phát hành phiên bản mới như blue-green hay canary để giảm thời gian gián đoạn.
Design Critique
Quy trình đánh giá thiết kế dựa trên mục tiêu và người dùng thay vì sở thích cá nhân.
Design Debt
Nợ thiết kế tích lũy từ các giải pháp tạm thời. Cần được giải quyết qua việc kiểm tra thiết kế định kỳ.
Design Handoff
Quy trình chuyển giao đặc tả thiết kế từ designer sang kỹ sư, thường qua Figma hoặc Zeplin.
Design Sprint
Quy trình 5 ngày của Google để xác thực ý tưởng: Định nghĩa, Phác thảo, Quyết định, Tạo mẫu và Kiểm thử.
Design System
Hệ thống nền tảng bao gồm các token, thành phần và hướng dẫn. Giúp tăng tốc độ phát triển.
Design Token
Các biến đại diện cho giá trị thiết kế như màu sắc. Giúp giữ thiết kế và mã nguồn luôn đồng bộ.
Desktop-First
Phương pháp thiết kế ưu tiên màn hình lớn rồi thu nhỏ. Hiện nay Mobile-First được khuyến nghị hơn.
DevOps
Văn hóa và các thực hành tích hợp giữa phát triển (Dev) và vận hành (Ops) để cung cấp phần mềm tin cậy hơn.
DHCP
Giao thức tự động cấp phát địa chỉ IP cho các thiết bị khi chúng kết nối vào mạng.
DI (依存性の注入)
Tiêm phụ thuộc. Mô hình thiết kế nơi các phụ thuộc được truyền từ bên ngoài, giúp thành phần dễ kiểm thử hơn.
DI Container
Tính năng của framework giúp quản lý việc tiêm phụ thuộc. NestJS cung cấp tính năng này cho ứng dụng lớn.
Dialog / Modal
Giao diện lớp phủ yêu cầu sự chú ý của người dùng. Cần thuộc tính aria-modal để đảm bảo khả năng tiếp cận.
Diffusion Model
Mô hình AI tạo dữ liệu bằng cách loại bỏ nhiễu dần dần. Stable Diffusion sử dụng mô hình này để tạo ảnh.
Directory Traversal
Kiểu tấn công dùng ../ để truy cập trái phép vào các tệp ngoài thư mục gốc. Ngăn chặn bằng làm sạch đường dẫn.
Distributed Lock
Cơ chế ngăn chặn nhiều tiến trình sửa đổi cùng một tài nguyên trong môi trường phân tán (thường dùng Redis).
Distributed Tracing
Kỹ thuật trực quan hóa luồng yêu cầu đi qua các microservices. Các công cụ tiêu biểu là OpenTelemetry.
DKIM
Giao thức xác thực email bằng chữ ký số để xác nhận tính chính danh của tên miền gửi email.
DMARC
Email policy using SPF and DKIM to prevent spoofing and define handling of failed checks.
DNS
Domain Name System. Translates domain names to IP addresses. Propagation can take up to 48 hours.
DNS Lookup
Process resolving a domain name to an IP address. Involves recursive and iterative resolution steps.
DNS TTL
Time in seconds a DNS record is cached. Too short increases name resolution load and hurts performance.
Docker
Containerization platform. Packages environments into containers to run identically anywhere.
Docker Compose
Tool defining and managing multi-container Docker setups with a YAML file. Widely used for local dev environments.
DOM
Document Object Model. Tree API allowing JavaScript to manipulate HTML documents.
Domain Model
Classes and objects representing business concepts and logic. The central artifact of Domain-Driven Design.
Double Diamond
UK Design Council model with 4 phases: Discover, Define, Develop, Deliver.
Drag & Drop API
HTML5 API enabling drag-and-drop interactions natively in the browser.
Drizzle ORM
Lightweight, SQL-first TypeScript ORM with type safety and near-raw-SQL ergonomics.
Dropout
Regularization technique randomly disabling neurons during training to prevent overfitting.
Dynamic Import
Asynchronous module loading with import() syntax. The basis for code splitting and lazy loading.
Dynamic Secrets
Generating unique, short-lived secrets per request via Vault. Minimizes exposure from credential leaks.
DynamoDB
AWS fully managed key-value and document NoSQL DB. Known for scalability and single-digit ms latency.
Data Anonymization
Process of removing or modifying personally identifiable information from data sets.
Data Governance
Collection of processes and standards that ensure the effective and efficient use of information.
Data Lineage
Metadata describing the origins, movements, and transformations of data over time.
Data Mesh
Decentralized data architecture that organizes data by specific business domains.
Data Pipeline
Set of automated processes that move data from a source to a destination.
Deadlock Prevention
Techniques used in computing to ensure that a system never enters a deadlock state.
Declarative Programming
Programming paradigm expressing the logic of a computation without describing its control flow.
Dependency Cycle
Situation where two or more modules depend on each other, creating a circular reference.
Deterministic Algorithm
Algorithm that, given a particular input, will always produce the same output through the same states.
Diffusion Model
Gen AI models that create data by learning to reverse a process of adding noise to images.
Digital Twin
Virtual representation of a physical object or system that uses real-time data for simulation.
Direct Manipulation
Interaction style in which users act directly on visual objects to perform tasks.
DDoS Protection
Security measures designed to mitigate the impact of distributed denial-of-service attacks.
Dynamic Analysis
Testing and evaluation of an application by executing the program in a real-time environment.
E Nhóm
E2E Test
End-to-End Test. Simulates real user interactions in a browser to verify the entire system stack.
ECB Mode
AES mode where identical plaintext blocks produce identical ciphertext. Reveals patterns; must be avoided.
Edge Computing
Executing logic on CDN edge servers close to users for ultra-low latency.
Elasticsearch
Distributed full-text search engine based on Apache Lucene. Widely used for log analysis and product search.
ELK Stack
Elasticsearch, Logstash, Kibana combo for collecting, analyzing, and visualizing logs.
Embedding
Dense vector representing the meaning of text or images. Foundation of semantic search and RAG.
Emotion
CSS-in-JS library known for performance and flexibility. Used by MUI and many other UI libraries.
Empathy Map
UX canvas visualizing a user's thoughts, feelings, actions, and words. Often precedes persona creation.
Empty State
UI shown when there's no content. Good empty states guide users toward the next action rather than showing blank space.
Encoder-Decoder
Neural network structure encoding input into a representation and decoding it to output. Used in translation and segmentation.
Encryption at Rest
Encrypting stored data on disk. Prevents data exposure if storage media is physically stolen.
Encryption in Transit
Encrypting data as it travels over networks. Implemented with TLS/HTTPS to prevent eavesdropping.
Enum
TypeScript type defining a set of named constants. String enums retain their values after compilation.
Envoy
High-performance proxy for service meshes developed by Lyft. Widely used as Istio's data plane.
Envoy Proxy
High-performance C++ proxy for edge and service mesh. Used as Istio's sidecar for L7 traffic control.
Error Boundary
React mechanism that catches JS errors in component trees and shows fallback UI instead of crashing.
Error Handling Strategy
App-wide strategy for managing errors using try/catch, error boundaries, and global error handlers.
Escape (エスケープ)
Converting special characters to safe forms. Context-aware escaping is critical for preventing XSS.
ESM
ECMAScript Modules. JavaScript's standard module system using import/export. Natively supported in Node.js.
etcd
Distributed key-value store used by Kubernetes for config and state management.
Event Delegation
Handling events on a parent element instead of individual children. Memory-efficient pattern.
Event Loop
Mechanism enabling async operations on a single thread in Node.js and browsers, coordinating with callback queues.
Event Sourcing
Storing state as a sequence of events rather than current values. Enables audit trails and replay.
Event-Driven Architecture
Architecture where services communicate via async events, enabling loose coupling.
EventEmitter
Node.js class enabling event-driven communication between objects. The basic implementation of Pub/Sub.
EXPLAIN / Query Plan
Command revealing a SQL query's execution plan. Visualizes index usage and bottlenecks for optimization.
Exponential Backoff
Retrying failed requests with exponentially increasing intervals to avoid overloading the server.
Eye Level Design
Designing the viewport-visible area strategically. Ensures critical content appears at eye level without scrolling.
Eye Tracking
UX research tech measuring exactly where users look. Visualizes attention hotspots and scan patterns.
ESI (Edge Side Includes)
Markup language used to assemble dynamic web content at the caching edge of a network.
E-commerce Conversion
The percentage of website visitors who complete a desired action, such as making a purchase.
Elasticsearch Ranking
The process by which Elasticsearch determines the order of search results based on relevance.
Engineering Metrics
Data points used to measure the efficiency and quality of a software engineering team.
Entity Framework
An open-source ORM framework for ADO.NET, part of the .NET ecosystem.
Ephemeral Environment
Short-lived, disposable environment created for testing a specific feature or pull request.
Error Budget
The amount of allowed unreliability in a service before the development of new features must stop.
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F-Pattern
Eye-tracking finding that users scan pages in an F-shape. Place key content top-left accordingly.
Failover
Automatic switch to standby when primary fails. RPO and RTO are key metrics for failover design.
Favicon
Small icon shown in browser tabs and bookmarks. SVG format is the modern best practice.
FCP
First Contentful Paint. Time until the browser renders the first text or image. A key Web Vitals metric.
Feature Detection
Checking at runtime whether a browser supports an API before using it. More reliable than User-Agent detection.
Feature Flag
Toggling features on/off without code changes. Used for A/B tests and gradual rollouts.
Feedback Loop (UX)
UI immediately responding to user actions to confirm success or failure of their input.
Few-Shot Learning
ML approach learning from very few examples. Includes few-shot prompting by adding examples to LLM prompts.
FID
First Input Delay. Time from first user interaction to browser response. One of the Core Web Vitals.
FIDO2 / Passkey
Password-free login using device-bound cryptographic keys. Highly phishing-resistant standard.
FIFO Queue
First In First Out queue. Processes messages in the order received. The basic structure of message brokers.
Figma
Cloud-based UI design tool. Real-time collaboration, prototyping, and design system management.
File-based Routing
Routing where file/folder structure maps directly to URL paths. Used by Next.js, Nuxt, and SvelteKit.
Fine-Tuning
Further training a pre-trained model on domain-specific data to specialize its performance.
Firebase
Google's BaaS for mobile and web. Bundles Realtime DB, Firestore, Auth, and Hosting.
Fitts' Law
UI law: targets should be large and close. Time to reach a target scales with distance and size.
Flat Design
Design style using only simple shapes, colors, and typography without shadows or depth. Contrasts with Material Design.
Flexbox
CSS 1D layout model. display:flex enables flexible arrangement of children in row or column.
Fly.io
Cloud PaaS deploying containers globally. Runs apps close to users for low latency.
Focus Trap
Keeping keyboard focus inside a modal while it's open. Essential for keyboard accessibility.
Font Pairing
Combining different fonts for headings and body text to create typographic hierarchy and visual interest.
Font Subsetting
Extracting only used characters from a web font to reduce file size. Especially impactful for CJK fonts.
font-display
CSS property controlling how a web font displays during loading. 'swap' avoids invisible text.
Foreign Key
Column referencing another table's primary key. Enforces referential integrity in relational databases.
Form Accessibility
Form accessibility practices: linking labels, error messages with aria-describedby, and focus management.
Form Validation
Validating user input against rules. Often combined with react-hook-form and Zod in modern React.
Formatter
Tool that rewrites code to enforce consistent styling. Prettier is the industry standard.
Foundation Model
Large pre-trained model applicable to many tasks. GPT, Claude, and Gemini are prominent examples.
Framer Motion
Declarative animation library for React. Implements complex animations with a simple API.
Full-Text Index
DB feature storing words in an inverted index for fast full-text search queries.
Full-Text Search
Searching entire document content using inverted indexes. Elasticsearch and Postgres pg_trgm are common.
Function Calling
LLM feature generating structured JSON arguments to invoke external APIs and tools. Key for AI agents.
Feature Engineering
Process of using domain knowledge to extract features from raw data that improve AI model performance.
Federated Learning
Machine learning technique that trains an algorithm across multiple decentralized devices holding local data.
File System API
Web API providing methods for reading and writing files and directories on the local file system.
FinOps
Framework for managing cloud operating expenses to balance speed, cost, and quality.
Flux Architecture
Application architecture used by Facebook for building client-side web applications with unidirectional data flow.
Focus Ring
Visual indicator showing which element currently has keyboard focus, critical for accessibility.
Frontend Infrastructure
Foundational tools and processes that support the development and delivery of web frontends.
Full Stack Trace
Report showing the sequence of function calls that led to an error during program execution.
Functional Programming
Programming paradigm where programs are constructed by applying and composing pure functions.
Fuzzy Matching
Technique of finding strings that match a pattern approximately rather than exactly.
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GAN
Generative Adversarial Network. Generator and discriminator compete to produce realistic data.
Garbage Collection
Automatic reclaiming of unused memory. Used by Java, Go, JavaScript, and Python runtimes.
Gateway Pattern
Design pattern wrapping external service access for abstraction. Hides implementation details and enables swapping.
GCP
Google Cloud Platform. Known for BigQuery, Vertex AI, Cloud Run, and other cloud services.
Geo-Replication
Replicating data across geographically separated regions for disaster recovery and low-latency local access.
Gestalt Principles
Perceptual patterns (proximity, similarity, continuity) applied to group elements in UI design.
Git
Distributed version control system. Manages history and enables team collaboration via GitHub/GitLab.
Git Flow
Git branching strategy using feature, release, and hotfix branches for structured development.
Git Hooks
Scripts automatically running on Git events like pre-commit and pre-push. Managed with Husky.
Git Repository
Data store holding all code and its Git history. Exists as local and remote (GitHub/GitLab) copies.
GKE
Google Kubernetes Engine. Google Cloud's managed Kubernetes service.
Golden Ratio
Ratio of ~1:1.618. Found in nature and used in typography and layout for aesthetically pleasing proportions.
GPT
Generative Pre-trained Transformer. OpenAI's LLM series. GPT-4 powers ChatGPT.
GPU
Graphics Processing Unit. Massively parallel processor essential for training and running deep learning.
Graceful Shutdown
Server shutdown implementation completing in-flight requests before exiting to maintain data integrity.
Grafana Loki
Lightweight log aggregation system designed like Prometheus. Integrates natively with Grafana.
GraphQL
API query language. Clients specify exactly which fields they need, avoiding over/under-fetching.
GraphQL Federation
Architecture exposing multiple GraphQL APIs as a unified schema. Apollo pioneered the specification.
GraphQL Subscription
GraphQL operation type pushing real-time data from server to client over WebSocket.
Grid System
Layout foundation dividing the page into equal columns. 12-column grids are standard in web design.
Grounding
Anchoring LLM outputs to external verified sources to reduce hallucinations.
gRPC
Google's RPC framework using Protobuf and HTTP/2 for fast, type-safe inter-service communication.
gRPC Streaming
gRPC bidirectional streaming allowing real-time data exchange between client and server.
Guardrails
Controls preventing LLM outputs from being harmful or inaccurate via filtering and system prompts.
Guerrilla Testing
Quick, cheap UX research gathering feedback from random people, often in cafes.
gzip
Standard HTTP response compression. Enabling it on Nginx or CDN reduces transfer size significantly.
Game Loop
The central loop in a game program that processes inputs, updates game state, and renders the frame.
Generic Programming
Style of computer programming in which algorithms are written in terms of types to-be-specified-later.
Gestalt Proximity
Design principle stating that objects near each other tend to be perceived as a group.
Git Rebase
Git operation that rewrites commit history by moving a series of commits to a new base commit.
Golden Signals
Four critical metrics for monitoring service health: Latency, Traffic, Errors, and Saturation.
GPU Acceleration
Using a Graphics Processing Unit to speed up compute-intensive tasks like rendering or AI training.
GraphQL Introspection
The ability for a GraphQL client to query a schema for information about what queries it supports.
Green Computing
Practices and technologies aimed at reducing the environmental impact of computing systems.
Git Stash
Git command that temporarily shelves changes made to a working directory to clean it up.
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Hallucination
LLM generating confident but factually incorrect content. Mitigated by RAG and fact-checking.
Haptic Feedback
Vibration feedback responding to touch. Improves realism and confirmation of actions in mobile UI.
Hardening
Disabling unnecessary features and services to minimize a system's attack surface.
HashiCorp Vault
General-purpose secret management tool for secrets, certs, and keys. Supports dynamic secret generation.
Headless CMS
Content Management System providing pure content via APIs, decoupling it from the frontend.
Headless UI
UI components providing behavior and accessibility without styles. Radix UI and Headless UI are popular.
Health Check
HTTP endpoint or command for load balancers and Kubernetes to verify service health. Typically at /health.
Helm
Kubernetes package manager using Charts to template and manage deployments.
Heuristic Evaluation
Usability inspection where experts evaluate UI against heuristics like Nielsen's 10 principles.
HEX
Color notation in #RRGGBB format. Standard in CSS. 8-digit form includes alpha transparency.
High Availability (HA)
Design principle maximizing uptime. Expressed as SLA percentages like 99.9% or 99.99%.
High-Fidelity Prototype
Interactive prototype closely resembling the final product. Used for user testing and dev handoff.
HMAC
Hash-based MAC using a secret key to verify message integrity and authenticity.
Honeypot
Decoy server or field luring attackers. Used to observe attack patterns or detect bots.
Horizontal Scaling
Scaling by adding more server instances. Contrasts with vertical scaling (upgrading server specs).
Hot Reload
Dev feature that applies code changes instantly without full page reload, preserving app state.
Hot Standby
Standby DB replica ready to take over immediately if the primary fails, minimizing failover time.
Hover State
UI element state on mouse hover. Communicates interactivity and affordance to the user.
HSL
CSS color model using Hue, Saturation, and Lightness. More intuitive for designers than RGB.
HTML Streaming
Server sending HTML to the browser incrementally as it generates it. Reduces time to first byte.
HTML5
Fifth revision of HTML. Added semantic tags, Canvas, Web Storage, Web Workers, and more.
HTTP Caching
Using Cache-Control and ETag headers to cache responses in browsers and proxies.
HTTP Idempotency Keys
Unique key attached to API requests enabling safe retries of duplicate requests after network failures.
HTTP Methods
HTTP operation types: GET, POST, PUT, PATCH, DELETE. The foundation of RESTful API design.
HTTP Status
200=OK, 400=Bad Req, 404=Not Found, 500=Server Error. Basic way to diagnose API responses.
HTTP/2
Modern HTTP protocol allowing multiplexing (multiple requests per connection), speeding up page loads.
HTTP/3
Latest HTTP version using QUIC over UDP. Faster connection setup and better packet loss resilience.
Hydration
Attaching JavaScript to server-rendered HTML to make it interactive on the client. Key in Next.js and Nuxt.
Hydration Mismatch
Error when SSR HTML doesn't match client render output. Often caused by dates, random values, or browser APIs.
Hyperparameter
Config values like learning rate and batch size controlling the training process, not learned from data.
Hystrix
Netflix's Java circuit breaker library. Now in maintenance mode; Resilience4j is the recommended successor.
Hydration (UX)
The process of attaching JavaScript to server-rendered HTML to make it interactive.
Hardware Acceleration
The use of specialized computer hardware to perform functions faster than is possible using custom software.
Hash Collision
Situation that occurs when two distinct inputs produce the same output hash value.
Headless Browser
Web browser without a graphical user interface, controlled programmatically for testing.
Heuristic Usability
Usability inspection method where evaluators compare a UI against a set of recognized design principles.
High Availability
System design approach providing a high level of operational performance and uptime.
Horizontal Sharding
Database partitioning pattern that separates rows of a table across multiple database instances.
Human-in-the-loop
Process where humans and AI interact to improve the accuracy and accountability of an automated system.
HSTS
Security header that forces browsers to interact with a website only via HTTPS.
Huffman Coding
Algorithm used for lossless data compression based on the frequency of occurrence of characters.
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i18n
Numeronym for Internationalization. Designing apps to support multiple languages and locales.
IaC
Infrastructure as Code. Managing infrastructure configuration as code with Terraform or Ansible.
IAM
Identity and Access Management. Controls who can do what to which resources. AWS IAM is the prime example.
Icon Design
Visual symbol representing actions or concepts. Consistency, clarity, and sizing are key considerations.
Idempotency
Property where repeating the same operation has the same result. GET, PUT, DELETE are idempotent.
IdP
Identity Provider. Manages identities and asserts them to other services. Auth0 and Okta are examples.
IDS / IPS
Intrusion Detection/Prevention System. Detects and blocks unauthorized network or host access.
iframe
HTML element embedding another web page. Requires careful security with sandbox and CSP restrictions.
Image Optimization
Combining WebP conversion, compression, lazy loading, and proper srcset to speed up page loads.
Image Segmentation
Computer vision task classifying each pixel into a class. Used in autonomous driving and medical imaging.
Image Sprite
Combining multiple images into one to reduce HTTP requests. Position controlled via CSS background-position.
Immer
Library allowing mutable-style updates to immutable state. Often combined with Zustand or Redux Toolkit.
Immutable Infrastructure
Operational practice always deploying fresh images instead of modifying servers. Prevents configuration drift.
Indent
Code indentation. Essential for readability. Usually 2 or 4 spaces.
Index File
Default file for a directory (index.html, index.ts). Entry point accessible by path without specifying the filename.
Inference
Using a trained model to make predictions. Latency and cost optimization are key concerns.
Information Architecture
Discipline structuring and organizing content for effective navigation and findability.
Ingress
Kubernetes resource managing external HTTP routing into cluster services. Also handles TLS termination.
Ingress Controller
Controller implementing Kubernetes Ingress rules. Nginx Ingress Controller and Traefik are popular options.
INP
Interaction to Next Paint. Measures responsiveness from user input to next paint. Replaced FID in Core Web Vitals.
Input Debounce
UX pattern waiting for a pause in typing before sending an API request, avoiding per-keystroke calls.
Input Event
DOM events for keyboard, mouse, and touch interactions. The input event is standard for text input handling.
Insecure Deserialization
Vulnerability where deserializing untrusted data leads to arbitrary code execution. A recurring OWASP Top 10 item.
Instruction Tuning
Fine-tuning LLMs on instruction-formatted data to improve their ability to follow user directions.
Integration Test
Test verifying that multiple modules or services work together correctly.
Interaction Cost
Total cognitive and physical effort (clicks, scrolls, decisions) required for a user to reach their goal.
Intersection Observer
Browser API efficiently watching when elements enter the viewport. Used for lazy loading and infinite scroll.
IP Address
Network address identifying a device. IPv4 is 32-bit (e.g. 192.168.0.1); IPv6 is 128-bit.
IP Allowlist
Allowing requests only from specified IP addresses. Used to restrict access to admin panels.
IPC
Inter-Process Communication. Mechanisms for data exchange between processes: pipes, sockets, shared memory.
Island Architecture
Rendering pattern placing interactive JS components as 'islands' in otherwise static HTML. Used by Astro.
Isomorphic / Universal JS
Design where the same JS code runs on both server and client. Adopted by Next.js and Nuxt.
Istio
Service mesh for Kubernetes providing traffic management, mTLS auth, and observability declaratively.
Idempotency
Property of certain operations that can be applied multiple times without changing the result beyond the initial application.
Immutable Infrastructure
Approach to managing software services where components are replaced rather than changed in place.
Incremental Build
Software build process that only recompiles or re-links files that have been modified.
Index Scan
Retrieval technique where a database searches through an index to find specific row locations.
Indicator (UI)
Visual element like a badge or light that communicates the state or progress of a process.
In-memory Database
Database management system that primarily relies on main memory (RAM) for data storage.
Inode
Data structure on a file system that stores information about a file or directory, except its name and content.
Input Latency
Delay between a user action (like a click) and the response being visible on the screen.
Instruction Set
Complete set of commands that a CPU can understand and execute directly.
Intranet
Private network accessible only to an organization's staff, isolated from the public internet.
Inverted Index
Index data structure storing a mapping from content, such as words, to its locations in a document set.
I/O Bound
Condition in which the time it takes to complete a computation is determined by the period spent waiting for I/O operations.
IoT (Internet of Things)
Network of physical objects embedded with sensors and software for connecting and exchanging data.
IP Spoofing
Creation of IP packets with a false source IP address to impersonate another computer system.
ISA (Instruction Set Architecture)
Abstract model of a computer that defines the set of instructions the CPU can execute.
ISM (Industrial, Scientific and Medical band)
Radio frequency bands reserved internationally for industrial, scientific, and medical purposes.
Isomorphic JavaScript
JavaScript applications that can run both on the client and the server using the same code.
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Jamstack
JavaScript, APIs, Markup architecture. Decouples static UI from dynamic backends.
JavaScript Runtime
Engine and environment executing JavaScript. V8/SpiderMonkey in browsers; Node.js, Deno, Bun on servers.
Jenkins
Open-source CI/CD automation server. Highly extensible with a large plugin ecosystem.
JIT Compiler
Just-In-Time compiler. Converts code to native at runtime for speed. Used in JVM and V8.
Job Queue
Task queue for running slow jobs (email, image processing) asynchronously. Bull/BullMQ are popular.
Jobs to Be Done
Framework focusing on the fundamental motivation (job) driving users to adopt a product.
Jotai
Simple atom-based React state management library. Inspired by Recoil with a minimal API.
JPEG
Lossy compression image format for photos. No transparency, but universally supported.
jsdom
Library emulating browser DOM APIs in Node.js. Used as the DOM environment in Jest and other test runners.
JSON
JavaScript Object Notation. Standard lightweight key-value format for APIs.
JSON Schema
Specification for validating JSON data structure and types. Used for API request and response definitions.
JSON-LD
JSON format for Schema.org structured data to communicate page semantics to search engines.
JSONB
PostgreSQL binary JSON storage type. Supports indexing on keys for fast queries, outperforming the json type.
JSX
Syntax extension for writing HTML-like UI inside JavaScript. Used in React, transpiled by Babel.
JWT
JSON Web Token. Widely used for auth. Payload is readable by anyone, but signature detects tampering.
JWT Best Practices
JWT security guidelines: reject alg:none, use short expiry, prefer RS256/ES256, always transmit over HTTPS.
JWT Refresh Token
Long-lived token used to issue new short-lived access tokens. Regular rotation is recommended.
Jitter
Variation in the delay of received packets, which can cause distortions in real-time communication.
JIT Compiler
Compilation done during the execution of a program at runtime, rather than prior to execution.
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k6
Modern load testing tool with JavaScript scripting. Easy to integrate into CI/CD pipelines.
Kerning
Adjusting space between specific letter pairs for visually even text spacing.
key prop
Unique identifier on each React list item helping the reconciler efficiently diff and update lists.
Keyframe
Defined style state at a specific point in a CSS animation. Written with @keyframes using from/to or %.
Keylogger
Software or hardware recording keystrokes. Used as malware to steal credentials.
Knowledge Graph
Database representing entities and their relationships as a graph. Enhances RAG and search accuracy.
Kubernetes (K8s)
Container orchestration system. Automates deployment and scaling of massive container clusters.
Kubernetes RBAC
Kubernetes Role-Based Access Control. Manages permissions for users and service accounts with Roles and Bindings.
KV Cache
Caching Key/Value matrices in Transformer attention to avoid recomputation. Significantly speeds up inference.
Kanban
Visual system for managing work as it moves through a process, often used in agile development.
Kerberos
Computer network authentication protocol that works on the basis of tickets to allow nodes to communicate securely.
Keyframe Animation
Technique where the start and end points of a transition are defined, and intermediate frames are automatically generated.
Kubernetes (K8s)
Open-source system for automating deployment, scaling, and management of containerized applications.
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l10n
Numeronym for Localization. Adapting an i18n app for a specific locale, including dates and currency.
LangChain
Python/TS framework for building LLM apps. Widely used for RAG pipelines and agent construction.
LangSmith
Platform by LangChain for debugging, testing, evaluating, and monitoring LLM applications.
Latency
Delay from request to response. Analyzed with percentiles like p50, p95, p99.
Latent Space
High-dimensional vector space where a model encodes input data. Nearby points share semantic similarity.
Layout Shift
Page elements shifting due to late-loading images or fonts. Prevented by specifying explicit width/height.
Lazy Image Loading
Performance technique loading off-screen images lazily using IntersectionObserver or loading='lazy'.
Lazy Loading
Loading components or routes only when needed. Splits bundles to improve Time to Interactive.
LCP
Largest Contentful Paint. Time for the largest content element to appear. A Google Core Web Vital.
LDAP
Lightweight Directory Access Protocol. Used in enterprise identity systems like Active Directory.
Leader Election
Algorithm electing a single leader among distributed nodes. Implemented with Raft in etcd and Zookeeper.
Leading (行送り)
Line spacing. Set with CSS line-height. Typically 1.5–1.7 recommended for body text readability.
Least Privilege
Security principle granting only the minimum permissions needed. Critical for IAM and DB design.
Lighthouse
Google's web quality tool. Scores Performance, Accessibility, SEO, and Best Practices out of 100.
lint-staged
Tool running linters and formatters only on staged files. Used for pre-commit quality checks.
Linter
Static code analysis tool that flags bugs or stylistic errors. ESLint is the primary example.
LlamaIndex
Python framework connecting LLMs with data. Simplifies ingestion, indexing, and querying pipelines.
LLM
Large Language Model. Pre-trained on massive text. Examples include GPT-4 and Claude.
LLM Evaluation
Methods for measuring LLM output quality: BLEU, ROUGE, human eval, and LLM-as-a-judge approaches.
Load Balancer
Hardware or software distributing traffic evenly across servers for high availability and throughput.
Loading State
UI state during async data fetching shown with skeletons, spinners, or placeholders.
localStorage
Browser API for persistent key-value storage. ~5MB limit, synchronous API. Part of Web Storage.
Log Aggregation
Collecting and centralizing logs from multiple services for searching and analysis. ELK Stack and Loki are common.
Log Level
Log severity hierarchy: DEBUG < INFO < WARN < ERROR < FATAL. Controls output volume in production.
LoRA
Low-Rank Adaptation. Efficient fine-tuning updating only a small fraction of model parameters.
Lottie
Lightweight animation library playing After Effects animations exported as JSON on web and mobile.
Low-Fidelity Prototype
Rough prototype using paper sketches or wireframes for early concept validation.
LRU Cache
Least Recently Used cache eviction policy. Removes the least recently accessed items first when full.
LSTM
Long Short-Term Memory RNN designed to learn long-range dependencies. Dominant before Transformers.
Lua
Lightweight scripting language embedded in games (Roblox), Nginx, and Redis.
L3 Cache
Level 3 cache, a memory bank built into the CPU that is shared among multiple cores.
Lerna
Tool for managing JavaScript projects with multiple packages in a single repository.
Lexical Scoping
Scoping method where the accessibility of variables is determined by their location in the source code.
LWP (Lightweight Process)
Unit of execution that shares the same address space and resources as other processes, like threads.
Linear Scanning
Simple search algorithm that checks every element in a list sequentially until a match is found.
Load Balanced Cluster
Group of servers that use a load balancer to distribute request traffic evenly.
LocalStorage Limit
The data storage cap for LocalStorage in a web browser, typically around 5 megabytes.
Logic Gate
Idealized model of computation or a physical electronic device implementing a Boolean function.
Long Polling
Web development technique used to push information from a server to a client as soon as data becomes available.
Low-code Development
Approach to software development that requires little to no coding to build applications and processes.
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map / filter / reduce
JavaScript's fundamental array transformation trio. Essential for functional-style data manipulation.
Markdown
Lightweight markup language using simple symbols for headings, lists, and links.
Materialized View
DB view storing precomputed query results on disk. Greatly speeds up complex aggregation queries.
MCP
Model Context Protocol. Anthropic's standard for LLMs to interact with external tools and data sources.
MD5
128-bit hash algorithm. Vulnerable to collision attacks; discouraged for modern security.
MDX
Markdown format supporting embedded JSX. Enables interactive components in docs and blog posts.
Media Query
CSS syntax switching styles based on screen size or device features. Written with @media.
Memoization
Caching function results to skip recalculation for identical inputs. Only valid for pure functions.
Memory Leak
Program failing to release unused memory, causing it to accumulate. Leads to OOM errors in long-running servers.
Mental Model
User's subjective understanding of how a system works. Good UI matches users' mental models.
Message Broker
Middleware mediating async messages between services. Kafka, RabbitMQ, and SQS are common choices.
Message Queue
FIFO queue for asynchronous inter-service communication. Decouples producers and consumers for resilience.
Message Schema
Schema defining message structure in brokers like Kafka. Avro and Protobuf are common formats.
MFA / 2FA
Multi-Factor Authentication. Combining password with possession (e.g. phone) to highly secure accounts.
Micro Frontend
Architecture splitting the frontend into independent apps per team. Frontend equivalent of microservices.
Microcopy
Short UI text on buttons, labels, errors, and placeholders. Has outsized impact on UX.
Microinteraction
Small, contained interactions like button animations or notification badges giving user feedback.
Microservices
Structuring an app as a collection of small, independent services. Scalable but complex to manage.
Middleware
Logic running between request and response. Used for auth, logging, and CORS.
Minify
Removing whitespace and comments to drastically reduce file sizes for production.
MITM
Man-in-the-Middle attack intercepting and potentially altering communications. TLS/HTTPS prevents it.
Mixture of Experts
Architecture activating only a subset of 'expert' modules per input. Enables efficient scaling.
MLOps
Practices for production ML: experiment tracking, model registry, and continuous monitoring.
Mobile-First
Design approach starting from the smallest screen and enhancing for larger screens. The recommended modern approach.
Modal
Overlay demanding user interaction before proceeding. Overuse hurts UX; use sparingly.
Model Distillation
Transferring knowledge from a large teacher model to a smaller student model for efficient inference.
Module Federation
Webpack feature allowing multiple builds to share components at runtime. Key for micro frontends.
Module System
System for splitting JavaScript code into files. ES Modules (import/export) is the current standard.
MongoDB
Document-oriented NoSQL DB storing data in JSON-like BSON format with schema flexibility.
Monolithic Architecture
Traditional architecture with all features in a single application. Simple but can become hard to scale and change.
Monorepo
Managing multiple projects in a single repository. Makes sharing code and managing versions easier.
Mood Board
Collage of images, colors, and textures defining the visual mood and direction of a design.
Motion Design
Using animation to communicate state changes, feedback, and navigation in UI.
mTLS
Mutual TLS. Both client and server authenticate with certificates. Used in zero-trust architectures.
Multi-Tenancy
SaaS design serving multiple customers from one app while isolating their data securely.
Multimodal AI
AI model processing multiple modalities like text, images, and audio. GPT-4V and Gemini are examples.
Mutation Observer
Browser API that asynchronously observes DOM mutations like added/removed nodes or attribute changes.
MVP
Minimum Viable Product. Delivering core value with minimal features to maximize learning and iteration.
MySQL
The most widely used open-source relational DB. Powers WordPress and countless web applications.
MCP
Model Context Protocol. An open standard for AI models to securely interact with external tools and datasets.
Micro-interactions
Small, subtle visual transitions or animations triggered by user actions like hovering or clicking.
Macro-task Queue
Queue in the JS event loop that handles tasks like timers, I/O, and UI rendering.
Man-in-the-middle (MITM)
Cyberattack where the attacker secretly relays and possibly alters the communications between two parties.
Markup Language
System for annotating a document in a way that is syntactically distinguishable from the text, like HTML.
Max Pooling
Sample-based discretization process in CNNs that selects the maximum value from a region.
Message Broker
Intermediary program module that translates a message from the formal messaging protocol of the sender.
Micro-task
Small, high-priority task in the JS event loop, such as Promise reaction or Mutation Observer.
Mixed Content
Situation where initial HTML is loaded over a secure HTTPS connection, but other resources are loaded over HTTP.
Mock Object
Simulated object that mimics the behavior of a real object in controlled ways for testing.
Monolithic Architecture
Software design where the entire application is built as a single, unified unit.
N Nhóm
N+1 Problem
ORM anti-pattern causing N extra queries for N records. Solved by eager loading or data loaders.
Namespace
Kubernetes logical grouping for resources. Used to separate teams or environments like dev/prod.
NATS
Lightweight, high-performance cloud-native messaging system supporting Pub/Sub, queues, and streams.
Negative Space
White space around elements. Intentional negative space improves readability and focus.
Neon
Serverless PostgreSQL cloud service with branching and scale-to-zero capabilities.
Neural Network
Machine learning model inspired by biological neurons. Composed of input, hidden, and output layers.
Next.js
React-based full-stack framework supporting SSR, SSG, and ISR. The most widely used React framework.
Next.js Middleware
Next.js feature processing requests at the Edge for redirects, rewrites, and header injection. Used for auth guards.
NextAuth.js
Authentication library for Next.js supporting OAuth, email, and credential-based login out of the box.
Nginx
High-performance web server and reverse proxy. Used for static files, load balancing, and TLS termination.
Nginx Config
Nginx configuration file declaratively defining virtual hosts, proxies, caching, and TLS via server/location blocks.
NLP
Natural Language Processing. Technology enabling computers to understand and process human language.
nmap
Open-source standard tool for scanning hosts and open ports on a network.
Nonce
Random value allowing specific inline scripts under CSP. Prevents replay attacks.
noop
Empty function doing nothing (no operation). Used as default callback or test stub.
NoSQL
Non-relational databases (MongoDB, Redis). Known for schema flexibility and high performance.
npm
Node Package Manager. The largest software registry used to install JavaScript libraries.
NPS
Net Promoter Score. Measures customer loyalty by asking likelihood of recommending the service (0-10).
Nuxt
Vue-based full-stack framework. The Vue equivalent of Next.js, with easy SSR and SSG support.
Naive Bayes
Simple probabilistic classifiers based on applying Bayes' theorem with strong independence assumptions.
NAS (Network Attached Storage)
File-level computer data storage server connected to a computer network providing data access.
Negative Lookahead
Regex syntax that matches a point where the following text does not match a specified pattern.
N-gram
Contiguous sequence of n items from a given sample of text or speech.
N+1 Problem
Inefficiency in ORMs where a single query for parent records triggers N additional queries for child records.
Non-volatile Memory
Type of computer memory that can retrieve stored information even after having been power cycled.
NoSQL (Non-relational)
Broad class of database management systems that differ from the traditional relational model.
O Nhóm
OAuth
Standard authorization protocol for delegating access without sharing passwords.
OAuth Scope
OAuth mechanism limiting what resources an access token can access. Applies the least privilege principle.
Object Detection
CV task detecting object locations with bounding boxes and classifying them. YOLO is a well-known model.
Object Storage
Storage format saving files in a flat namespace within buckets. S3 and GCS are examples. No directory hierarchy.
object-fit
CSS property controlling how img or video fills its container. Values include cover, contain, and fill.
Observability
System property enabling internal state visibility via the three pillars: logs, metrics, and traces.
Observer Pattern
Design pattern automatically notifying observers when an object's state changes. Related to useEffect.
OG Image
Image shown as thumbnail on social media shares. Next.js generates it dynamically via opengraph-image.tsx.
OGP
Open Graph Protocol. Meta tags defining title, desc, and image for social media link previews.
OIDC
OpenID Connect. Authentication layer on OAuth 2.0 issuing an ID Token. Foundation of SSO.
Onboarding
UX flow guiding new users to quickly understand and experience a product's core value.
Open Redirect
Vulnerability redirecting to unvalidated URLs, enabling phishing. Mitigated by whitelisting redirect destinations.
OpenAI API
HTTP API service providing access to OpenAI models. Endpoints include Chat Completions, Embeddings, and Vision.
OpenAPI
Standard YAML/JSON format for describing REST APIs. Combined with Swagger UI for auto-generated docs.
OpenAPI Spec
Machine-readable YAML/JSON describing REST API endpoints, parameters, and responses. Enables code generation.
OpenTelemetry
CNCF framework standardizing observability data collection for logs, metrics, and traces. Vendor-neutral.
Optimistic Locking
DB concurrency control checking a version number on update and requiring retry only on conflict.
Optimistic UI
Immediately updating UI assuming success before server responds. Rolls back on failure.
ORM
Object-Relational Mapping. Maps database tables to code objects, abstracting raw SQL queries.
ORM Lazy Loading
ORM behavior loading related data only when accessed. A common source of N+1 query problems.
Overfitting
Model fitting training data too closely, losing generalization. Addressed with dropout and regularization.
OWASP
Organization promoting web app security. OWASP Top 10 lists the most critical web vulnerabilities.
Oxc
Rust-based ultra-fast JS/TS toolchain providing a parser, linter, and transformer.
Open Source
Software with source code available for anyone to inspect, modify, and enhance. Maintained by communities.
OAuth 2.0
Industry-standard protocol for authorization that focuses on client developer simplicity.
Object Pool Pattern
Design pattern that uses a set of initialized objects kept in a pool rather than destroying them.
Observability (o11y)
The ability to measure the internal states of a system by examining its outputs (logs, traces, metrics).
Off-screen Rendering
The process of rendering content into a buffer other than the screen's main display area.
One-hot Encoding
Representation of categorical variables as binary vectors with a single high (1) bit.
OpenAPI Specification
Standard for describing RESTful APIs that allows both humans and computers to discover capabilities.
OpenID Connect (OIDC)
Simple identity layer on top of the OAuth 2.0 protocol for verifying user identity.
Operator Precedence
Collection of rules that reflect which procedures to perform first in a given mathematical expression.
OCR
Technology used to distinguish printed or handwritten text characters inside digital images of physical documents.
OSI Reference Model
Conceptual model that characterizes the communication functions of a telecommunication system into seven layers.
Overfitting
Modeling error that occurs when a function is too closely fit to a limited set of data points.
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package-lock.json
Lock file recording exact installed package versions. Guarantees reproducible builds across environments.
Pagination
Splitting large data into pages. Offset and cursor-based pagination differ in scale performance.
Pain Point
Friction or frustration a user experiences with a product. Discovered through UX research and addressed in design.
Participatory Design
Involving end users as co-designers in the design process. Directly incorporates stakeholder perspectives.
Password Hashing
Storing passwords as one-way hashes with bcrypt or Argon2. Plain SHA-256 is insufficient.
Path Traversal
Attack injecting path separators to read arbitrary files on the server outside the intended directory.
PEFT
Parameter-Efficient Fine-Tuning. Techniques like LoRA adapting models by training only a small subset of parameters.
Penetration Testing
Security assessment where experts simulate real attacks to find vulnerabilities.
Performance Budget
Constraints on page load time and asset sizes. Can be enforced automatically in CI pipelines.
Perplexity
Metric indicating how well a language model predicts text. Lower perplexity indicates better model quality.
Persistent Volume
Kubernetes storage resource persisting data beyond the lifecycle of individual containers.
Persona
Research-based profile of a typical user. Aligns design decisions and team communication.
pgvector
Open-source PostgreSQL extension adding vector storage and similarity search. Used for building RAG systems.
Phishing
Fraudulent sites or emails mimicking legitimate services to steal credentials. FIDO2/Passkeys resist this.
PKCE
OAuth 2.0 extension preventing authorization code interception attacks. Mandatory for SPAs and mobile.
PlanetScale
Serverless MySQL database platform known for its branching workflow for schema changes.
Playwright
Microsoft's E2E test framework. Tests Chromium, Firefox, and WebKit with one unified API.
PNG
Lossless image format supporting alpha transparency. Ideal for logos and screenshots.
pnpm
npm-compatible package manager with dramatically reduced disk usage and faster installs.
Pod
Kubernetes' smallest deployable unit. Groups containers sharing the same IP and storage volumes.
Polyfill
Code adding modern APIs to older browsers. Enables Promises, fetch, etc. in unsupported environments.
Portainer
Browser-based GUI for managing Docker and Kubernetes without command-line knowledge.
Positional Encoding
Mechanism adding position information to token embeddings in Transformers, which have no inherent order.
PostCSS
Tool transforming CSS with JavaScript plugins. Autoprefixer and Tailwind CSS run as PostCSS plugins.
PostgreSQL
Highly capable open-source relational DB. Beloved for JSON support, full-text search, and extensibility.
Preact
3KB React alternative with nearly identical API. Used where bundle size and performance are critical.
Prefetch
Pre-fetching resources the user is likely to need next to speed up navigation.
Prerendering
Server pre-generating and caching HTML. Similar to SSG but can handle dynamic requests.
Primary Key
Column uniquely identifying each DB record. Must be unique and non-null. Automatically indexed.
Prisma
Type-safe ORM for TypeScript. Auto-generates DB clients from schema and manages migrations.
Process Forking
OS feature creating child processes as copies of the parent. Node.js cluster module uses it to leverage multiple CPUs.
Progressive Disclosure
UX pattern revealing information progressively in response to user actions, reducing cognitive load.
Progressive Enhancement
Web strategy providing core content first, then enhancing for capable browsers.
Progressive JPEG
JPEG encoding displaying a blurry image first, then progressively sharpening. Improves perceived load speed.
Prometheus
Time-series metrics monitoring system. Typically paired with Grafana for visualization.
Prompt Engineering
Crafting inputs to get desired LLM outputs. Techniques include few-shot, CoT, and role prompting.
Prompt Injection
Attack overriding or bypassing an LLM's system prompt via malicious input. A key AI agent security concern.
Protocol Buffers
Google's binary serialization format. Faster and smaller than JSON. Used by gRPC.
Prototype Fidelity
How closely a prototype resembles the final product. Choose lo-fi or hi-fi based on what you're testing.
Pub/Sub
Messaging pattern where publishers send messages to subscribers. Enables loose coupling.
Pull Request
GitHub workflow requesting code review before merging to base branch. Also triggers CI/CD pipelines.
Pull to Refresh
Mobile pattern pulling screen down to refresh content. Popularized by iOS, now ubiquitous.
PWA
Progressive Web Apps. Makes web apps installable and offline-capable like native apps.
px (ピクセル)
Absolute unit (one screen dot). For responsive layouts, combining with rem/% is recommended.
P0 Priority
Highest level of importance for a bug or task that requires immediate attention and resolution.
Packet Switching
Digital networking communication method that groups all transmitted data into suitably sized blocks.
Page Fault
Interrupt raised by hardware when a running program accesses a memory page that is not in main memory.
Parity Bit
Bit added to a string of binary code that serves as a simple form of error detection.
Partial Application
Process of fixing a number of arguments to a function, producing another function of smaller arity.
Passkey
Passwordless authentication method using biometric sensors or PINs stored on a user's device.
Peer Review
Process where a software engineer's code is examined by colleagues to improve quality and maintainability.
Penetration Testing
Authorized simulated cyberattack on a computer system, performed to evaluate the security of the system.
Perceived Performance
How fast a user thinks a website or application feels, regardless of its objective load speed.
Persistent Connection
Digital communication link that remains open for further requests after the first request is completed.
Personalization (AI)
Process of tailoring experiences or content to an individual's context and preferences using AI.
PKI (Public Key Infrastructure)
Set of roles and policies needed to manage and distribute digital certificates and public-key encryption.
Pixel Density
Measurement of the number of pixels within a specific area of a screen, usually measured in PPI.
Point-to-Point (P2P)
Communications connection between two nodes or endpoints directly.
Poisoning Attack
Type of adversarial attack that pollutes the training data of an AI model to compromise its performance.
Polyglot Persistence
Concept of using different data storage technologies to handle varying data storage needs within a system.
Pre-rendering
Generating the content of a web page before it is actually requested to provide near-instant loading.
Predictive Analytics
Branch of advanced analytics that uses historical data and AI to make predictions about future outcomes.
Prefetching
Retrieving data from storage into a cache before it is actually needed to reduce latency.
Preflight Request
CORS request that checks to see if the CORS protocol is understood and a server is aware of specific methods.
Prepared Statement
Feature used to execute the same or similar database statements repeatedly with high efficiency and security.
Principle of Least Privilege
Security concept in which a user is given the minimum levels of access necessary to complete a task.
Private Endpoint
Interface that uses a private IP address from your virtual network to connect you privately to a service.
PAM (Privileged Access Management)
Framework of security technologies used to secure and monitor privileged user accounts.
Probabilistic Data Structure
Data structure that provides approximate answers to queries with a small, predictable error rate but low memory use.
Procedural Generation
Method of creating data algorithmically as opposed to manually, often used in video games.
Profiling Tool
Software tool used to analyze the performance of a computer program at the code level.
Promise.race
JS method that returns a promise that fulfills or rejects as soon as one of the promises in an iterable settles.
Proof of Work (PoW)
Consensus mechanism requiring participants to perform computational work to secure a network.
Property Descriptor
Metadata associated with an object property, describing its behavior like writability and enumerability.
Protocol Buffers (Protobuf)
Language-neutral mechanisms for serializing structured data, developed by Google.
Prototyping (UX)
Process of creating a preliminary model of a product to test concepts and get feedback.
Pure Function
Function that has no side effects and returns the same output for the same input every time.
Post-Quantum Cryptography
Cryptographic algorithms thought to be secure against a cryptanalytic attack by a quantum computer.
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QR Code
2D barcode storing URLs or text. Easily scannable by smartphone cameras.
Quantization
Converting model weights to lower precision (INT8) to speed up inference and reduce memory.
Query String
URL parameters after ? in key=value format. Used for filters, search queries, and pagination.
Qwik
Resumable framework delaying JS download and execution as long as possible for near-zero initial load.
Quadtree
Tree data structure in which each internal node has exactly four children, used for spatial indexing.
Quantum Cryptography
Encryption methods that leverage the principles of quantum mechanics to create secure communication.
Query Optimizer
Database component that examines many different strategies to execute a query and chooses the most efficient one.
Queue Backlog
The number of tasks or requests in a processing queue that are waiting to be executed.
R Nhóm
RabbitMQ
Popular AMQP-based message broker with sophisticated routing patterns and a rich plugin ecosystem.
RAG
Retrieval-Augmented Generation. Combining LLM with retrieved external knowledge for more accurate answers.
Rate Limit
Restricting the number of total requests a user can make to an API in a given timeframe.
Rate Limiting Algorithms
Rate limiting algorithms: Token Bucket, Leaky Bucket, and Fixed Window. Each suits different use cases.
RBAC
Role-Based Access Control. Assigning permissions to roles and roles to users.
React 18
React major version adding Concurrent Mode, enhanced Suspense, useTransition, and Server Components.
React Native
Framework using React's component model to build native iOS and Android apps.
React Portal
React feature for rendering children outside the parent DOM node. Ideal for modals and tooltips.
React Reconciler
React's algorithm computing Virtual DOM diffs and determining minimal DOM updates. Implemented as Fiber.
React Server Component
React 18 component running on the server without sending JS to the client. Reduces bundle size.
React.memo
React HOC that skips re-rendering when props haven't changed. Used for performance optimization.
Read Replica
Read-only DB instance replicated from the primary. Distributes read load and improves performance.
Recoil
Facebook's atom-based React state management library with declarative async selectors.
Recommender System
System predicting items a user will like based on history and preferences. Uses collaborative filtering and matrix factorization.
Redis
In-memory key-value store. Used for caching, sessions, Pub/Sub, and job queues due to its speed.
Redis Cluster
Redis distributed mode auto-sharding data across nodes for scale-out and high availability.
Redux
Predictable unidirectional state management library. Redux Toolkit greatly improved its developer experience.
Reflow
Browser recalculating element layout after DOM/CSS changes. Excessive reflows severely hurt performance.
Regex (正規表現)
Pattern matching for strings. Essential for validation, extraction, and replacing text.
Reinforcement Learning
ML paradigm where an agent learns a policy to maximize reward through trial and error with an environment.
Release Management
Process managing software version planning, testing, deployment, and announcement. Uses SemVer and CHANGELOG.
rem
Relative unit based on root font size. Accessible and highly recommended for responsive design.
Render Props
React pattern where a component accepts a function prop that returns JSX for logic reuse.
Replication
Copying DB data to multiple servers in real time. Read Replicas scale read-heavy workloads.
Repository Pattern
Pattern isolating DB access from business logic, making it easy to swap data sources.
requestIdleCallback
API scheduling low-priority tasks during browser idle time to minimize main thread impact.
Residual Network
Deep neural network with skip connections solving the vanishing gradient problem. ResNet is the prime example.
Resize Observer
Browser API efficiently watching element size changes. Used for responsive custom components.
Resource Hint
HTML tags (preload, prefetch, preconnect) instructing browsers to prioritize resource loading.
Responsive Images
Serving appropriately sized images using srcset and picture element based on screen and resolution.
Responsive Typography
Optimizing font size, line height, and line length based on screen size using clamp() and viewport units.
REST
Architectural style for APIs relying on HTTP methods and resource URLs. Simple and ubiquitous.
Retry with Backoff
Retrying failed requests with exponentially increasing delays. Add jitter to prevent thundering herd.
Reverse Proxy
Server sitting between client and backend, forwarding requests. Nginx and Caddy are common choices.
Reverse Proxy Cache
Nginx or Varnish caching API responses to reduce load on backend services.
RGB
Color model using Red, Green, Blue. The rgba() function adds alpha transparency support.
RLHF
Training models with human preference feedback. Technique used to align ChatGPT and Claude.
RLHF Fine-tuning
Fine-tuning using human feedback as reinforcement signal. Applied in ChatGPT and Claude development.
RNN
Recurrent Neural Network designed for sequential data. The predecessor to LSTM.
Rolling Update
Deployment method replacing servers one by one with a new version without stopping the service.
Route Guard
Middleware checking auth state before navigation, redirecting unauthorized access.
Route-Based Code Splitting
Splitting JS into per-route chunks so only the code needed for each page is loaded.
RPC
Remote Procedure Call. Invoking functions in another process over the network. gRPC uses Protobuf.
Runtime Type Checking
Validating type correctness at runtime since TypeScript types are erased at compile time. Zod is common.
Race Condition
Condition where the output of a process depends on the uncontrollable sequence of other events.
Radial Gradient
Pattern of color transitions that radiates from a central point outward in a circular shape.
RAM Latency
Delay that occurs between a memory component being asked for data and that data being available.
Raw Data Cleaning
Process of preparing data for analysis by removing or modifying data that is incorrect or incomplete.
RBAC (Role-Based Access Control)
Method of regulating access to computer or network resources based on the roles of individual users.
RDBMS
Database management system based on the relational model, using tables and SQL.
Reactive Programming
Programming paradigm concerned with data streams and the propagation of change.
RTB
Automated process of buying and selling digital advertising inventory in real-time.
Recurring Task
Task that repeats on a regular schedule, such as daily or weekly.
Recursive Function
Function that calls itself directly or indirectly to solve a problem by breaking it down into smaller instances.
Regression Testing
Verification that recent code changes have not adversely affected existing functional behavior.
Relational Algebra
Theoretical language for describing relational database operations using set theory.
Relay Topology
Network configuration where data is transmitted from one node to another in a chain-like fashion.
RPC (Remote Procedure Call)
Communication protocol that allows a program to execute a subroutine in another address space.
Render-blocking Resource
Script or stylesheet that must be processed before the browser can render a page.
Replication Lag
The time delay between a transaction happening on a primary database and appearing on a replica.
Request Smuggling
Vulnerability that occurs when different entities interpret an HTTP request in conflicting ways.
Resilient Design
Architecture that ensures a system continues to function despite failures in its components.
Resource Contention
Conflict over shared access to a resource, leading to decreased system performance.
Responsive Breakpoint
Specific screen width defined in CSS to change a website's layout for different devices.
Richardson Maturity Model
Model that breaks down the principal elements of a REST approach into four levels.
Ring Buffer
Circular data structure that wraps around to the beginning when it reaches the end.
Risk Assessment
Process of identifying and evaluating potential threats to a system or project.
Rooted Device
Android device that has been modified to give the user root access over the system.
Round Robin
Task scheduling algorithm that distributes requests across a set of resources in a circular order.
RSA Encryption
Asymmetric cryptographic algorithm based on the difficulty of factoring very large prime numbers.
Runtime Exception
Programming error that occurs while the code is running, rather than during compilation.
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Safe Area
Display region avoiding phone notches and home indicators. Controlled with CSS env() values.
Saga Pattern
Pattern managing distributed transactions across microservices. Uses compensating transactions on failure.
SAML
XML-based standard for enterprise SSO federation. Common in large organizations.
Sanitization
Removing or neutralizing dangerous content from user input. Used with escaping to prevent XSS and injection.
Sass / SCSS
CSS preprocessor adding variables, nesting, mixins, and inheritance. Written in .scss files.
SAST
Static Application Security Testing. Analyzes source code for vulnerabilities without executing it.
SBOM
Software Bill of Materials. Inventory of all components and dependencies. Used for vulnerability tracking.
Schema Validation
Runtime data shape validation with Zod or Yup. Used for forms and API request/response validation.
Scoped CSS
CSS applied only within a component's scope in Vue SFCs. Eliminates class name collisions.
Scroll Restoration
Restoring scroll position on browser back/forward navigation. May require manual implementation in SPAs.
Scrollytelling
Storytelling technique revealing content and animations as the user scrolls. Common in data journalism.
Secrets Manager
Service for securely storing and distributing secrets like API keys. AWS Secrets Manager is a prime example.
Secure Coding
Principles and practices for writing code that avoids vulnerabilities like injection and buffer overflow.
Security Audit
Systematic review of code and config from a security perspective, combining tools and manual review.
Security Headers
HTTP response headers like HSTS, X-Content-Type-Options, and Referrer-Policy hardening security.
SecurityHeaders.com
Tool grading HTTP security header configuration from A to F. Useful for assessing hardening completeness.
Semantic HTML
Using meaningful tags like header, nav, main, and article. Improves SEO and accessibility.
Semantic Release
Tool automating version bumping, CHANGELOG generation, and package publishing by analyzing commit messages.
Semantic Search
Search based on embedding vector similarity rather than exact keyword matching.
Semantic Similarity
Quantifying the semantic closeness of two texts using cosine similarity of their embedding vectors.
SemVer
Semantic Versioning format (Major.Minor.Patch) to communicate the nature of changes in releases.
Sentry
Error monitoring platform capturing, analyzing, and alerting on JavaScript errors in production in real time.
SEO
Search Engine Optimization. Strategies to improve ranking in search engines.
Server Component
React component executing only on the server. Safely accesses DBs and secrets without exposing them to clients.
Server-Sent Events
Simple HTTP-based API for one-way real-time push from server to client.
Serverless
Cloud architecture where the provider manages server ops, and you only pay for compute time.
Serverless Function
Cloud function executing code event-driven without managing containers or servers. AWS Lambda is the prime example.
Service Account
Non-human IAM account allowing applications and services to authenticate with cloud APIs.
Service Discovery
Mechanism for microservices to automatically locate each other. Consul and K8s DNS are common solutions.
Service Mesh
Infrastructure layer managing inter-service communication, security, and observability. Istio is the prime example.
Service Worker
Background browser script enabling caching strategies, push notifications, and offline PWAs.
sessionStorage
Web Storage API retaining data only for the current browser tab session. Cleared on tab close.
SHA-256
Hash function generating a 256-bit output. Used for integrity, secure hashing, and blockchain.
Shadow DOM
Part of Web Components that encapsulates a component's DOM and CSS from the outside world.
Sidecar Pattern
Pattern placing a helper container alongside the main one in the same Pod. Common in service meshes.
SIEM
Security platform aggregating logs and events for real-time threat detection and analysis.
Signals
Reactive values that notify subscribers when they change. Used in Angular, Vue Refs, and SolidJS for reactivity.
Single File Component
Component format bundling template, script, and style in one file. Popularized by Vue's SFC format.
Skeleton Screen
UI pattern showing grey placeholder shapes during loading. Considered better UX than spinners.
SLA
Service Level Agreement. Contract defining quality guarantees like uptime and response time.
SLO
Service Level Objective. Internal reliability target. Used with error budgets in SRE practices.
Slot
Vue/Web Components mechanism for parent to inject HTML content into a child. Equivalent to React children.
SLSA
Framework defining security maturity levels for software supply chains.
SMTP
Email sending protocol. Backend email is often delegated to services like SendGrid or Postmark.
Snowflake
Cloud-native data warehouse with a unique architecture separating storage and compute.
Socket.io
Node.js library simplifying real-time bidirectional communication with WebSocket fallback support.
SolidJS
Ultra-fast UI library updating the real DOM directly with reactive primitives, no virtual DOM.
Source Map
File mapping minified production code back to original source. Essential for debugging production errors.
SPA
Single Page Application. Rewrites the page dynamically with JS avoiding full reloads.
SPF
Email auth publishing authorized sending IPs in DNS. Prevents email spoofing.
Splash Screen
Initial screen showing logo/branding during app startup. Masks load time and reinforces brand.
SQL
Standard language for querying and manipulating relational databases.
SQL Injection
Attack injecting SQL into user input to manipulate the DB. Prevented with prepared statements.
SQL Window Function
SQL functions computing aggregates or rankings over partitions using OVER(). ROW_NUMBER and RANK are examples.
SSG
Static Site Generation. Generates HTML at build time for extreme performance via CDNs.
SSH
Secure Shell. Protocol for safely operating remote servers over an encrypted network connection.
SSL Pinning
Mobile app technique trusting only a specific TLS certificate. Strengthens resistance to MITM attacks.
SSL/TLS
Protocol that encrypts network communication. The 'S' in HTTPS.
SSO
Single Sign-On. Allows users to authenticate once and access multiple independent systems.
SSO with SAML
Enterprise SSO using SAML assertions exchanged between Identity Provider and Service Provider.
SSR
Server-Side Rendering. Generates HTML on the server per request. Great for SEO and fresh data.
SSR Streaming
React 18 technique streaming HTML chunks from server using Suspense. Improves TTFB.
Stable Diffusion
Open-source image generation diffusion model by Stability AI. Generates high-quality images from text locally.
Stale-While-Revalidate
Cache strategy serving stale data immediately while revalidating in the background. Balances UX and freshness.
State Machine
Defining finite states and transitions to manage complex UI state clearly. XState is the prime library.
Stateless Architecture
Design where servers hold no session state. Any instance can handle any request identically.
Sticky Element
UI element remaining fixed on screen while scrolling. Implemented with position: sticky. Used for nav and CTAs.
Stored XSS
XSS variant persisting malicious scripts in the DB, executing them in other users' browsers on page load.
Storybook
Tool for developing, documenting, and testing UI components in isolation. Essential for design systems.
strace
Linux tool tracing system calls of a process in real time. Used for debugging and performance investigation.
Structured Output
Constraining LLM output to a specific schema like JSON for reliable application integration.
Style Guide
Document defining colors, fonts, and component usage for a website. Part of a larger design system.
Subdomain Takeover
Vulnerability where DNS records pointing to deleted cloud resources allow attackers to take control.
Supabase
Open-source Firebase alternative built on PostgreSQL with realtime, auth, storage, and Edge Functions.
Supply Chain Attack
Attack injecting malicious code into trusted software dependencies or build pipelines.
SUS
System Usability Scale. Standardized 10-question survey quantifying system usability into a score.
Suspense
React mechanism declaratively showing fallback UI while async data loads. Also used for code splitting.
Svelte
UI framework that compiles away at build time. No virtual DOM, resulting in tiny, fast bundles.
SvelteKit
Svelte-based full-stack framework offering SSR, SSG, and serverless with simple configuration.
Swipe Card UI
Mobile UI pattern swiping cards left or right to approve or reject. Famous from Tinder's interface.
Swipe Gesture
UI interaction responding to finger swipes on touch devices. Used for navigation, deletion, and carousels.
SWR
Vercel's data fetching library implementing Stale-While-Revalidate strategy for auto caching and revalidation.
Symbol (JS)
JavaScript primitive creating globally unique values. Used for non-enumerable object keys and identifiers.
System Prompt
Special input defining the LLM's behavior, role, and constraints at the start of a conversation.
Skeleton Screen
UX pattern showing a placeholder layout while content is loading, reducing perceived latency.
SVG
Scalable Vector Graphics. XML-based image format that scales without losing quality. Perfect for web icons.
Sandbox
Isolated environment where software can be executed without affecting the rest of the system.
Scale-up (Vertical)
Increasing the capacity of a single machine by adding more CPU, RAM, or storage.
Scale-out (Horizontal)
Adding more machines to a system's pool of resources to handle increased load.
Schema Registry
Central repository for managing and sharing schemas between data producers and consumers.
SDK (Software Development Kit)
Set of tools, libraries, and documentation that help developers build apps for specific systems.
Search Intent
The underlying goal or reason why a user performs a specific search engine query.
Secondary Index
Index created on a set of fields other than the primary key to improve search efficiency.
Secure Boot
Security standard that prevents malicious software from loading when your PC starts up.
Sensing (AI)
Use of AI to interpret and react to data from sensors or environmental inputs.
Sentinel Value
Special value in a data structure that marks the end of a series or a specific condition.
Separation of Concerns
Design principle for separating a computer program into distinct sections based on their function.
Serialization
Process of converting an object into a format that can be stored or transmitted.
Serverless (FaaS)
Cloud computing model where the provider manages the server infrastructure and scales code on demand.
Service Mesh
Dedicated infrastructure layer for managing service-to-service communication in microservices.
Service Worker
Scripts that run in the background of a browser, enabling features like offline support and push notifications.
Session Fixation
Vulnerability that allows an attacker to hijack a valid user session by fixing the session ID.
Shader
Type of computer program used to calculate rendering effects on graphics hardware.
Shadow DOM
Web standard that allows for encapsulation of CSS and HTML within a component.
Shotgun Surgery
Code smell where a single change requires making many small edits to multiple classes.
Sidecar Pattern
Design pattern where an auxiliary container is attached to a primary application to extend its functionality.
Side Effect
Modification of some state outside of a function, in addition to returning a value.
Signal-to-Noise Ratio
Measure that compares the level of a desired signal to the level of background noise.
Signature-based Detection
Method used in antivirus software to identify malware by comparing files against a database of known patterns.
Single Source of Truth (SSoT)
Practice of structuring information models such that every data element is mastered in only one place.
Sinkhole
DNS redirection technique used to intercept and analyze malicious traffic.
Skeuomorphism
Design style where items represented resemble their real-world counterparts.
SLM (Small Language Model)
AI models with fewer parameters than LLMs, optimized for specific tasks or edge devices.
SNMP
Internet-standard protocol for collecting and organizing information about managed devices on IP networks.
Soft Delete
Operation that marks a record as deleted without actually removing it from the database.
Software Supply Chain
Anything that goes into or affects your code from development to production.
SOLID Principles
Five design principles intended to make software designs more understandable and flexible.
Source Map
File that maps transformed source code back to the original source to aid debugging.
Spaghetti Code
Unstructured and difficult-to-maintain computer code, named for its tangled flow.
Sparse Matrix
Matrix in which most of the elements are zero, requiring specialized storage formats.
Static Analysis
Automated analysis of source code without executing the program.
Sticky Session
Feature in load balancing that routes subsequent requests from a client to the same backend server.
Stop Word
Commonly used words that are filtered out before or after processing of natural language data.
Storage Class
Different tiers of data availability and cost for cloud object storage services.
Stream Processing
Computer programming paradigm that treats data as a continuous flow of events.
Stride (CNN)
Parameter in CNNs that determines the step size for moving a filter across an image.
Structural Integrity
The certainty that data is accurate, consistent, and follows defined storage rules.
Syntactic Sugar
Syntax within a programming language that is designed to make things easier to read or to express.
T Nhóm
Tag Manager
Tool like Google Tag Manager managing and deploying tracking scripts without code changes.
Tailwind CSS
Utility-first CSS framework. Build styles by composing small utility classes directly in HTML.
Taint & Toleration
Kubernetes mechanism adding constraints (Taint) to nodes, scheduling only Pods with matching Toleration.
TanStack Query
Library for declarative server state fetching, caching, and sync in React. Formerly React Query.
TanStack Table
Headless, framework-agnostic table library with declarative sorting, filtering, and pagination.
Task Analysis
Analyzing the steps, decisions, and actions required to complete a task. Used to optimize UI flows.
Task Flow
Specific path a user takes to complete a single task. More granular than a user flow.
TCP
Reliable, connection-based transport protocol. The foundation of HTTP/1.1.
TCP/IP Stack
Protocol suite powering internet communication. Four layers: Application, Transport, Internet, and Link.
TDD
Test-Driven Development. Writing failing tests first, then writing code to make them pass.
Telemetry
Collecting and analyzing app performance, errors, and usage data. APM tools leverage telemetry.
Temperature
Parameter controlling LLM output randomness. Near 0 is deterministic; above 1 is more creative.
Temporal
Workflow orchestration engine for running complex, long-running business logic with fault tolerance.
Terraform
HashiCorp IaC tool. Declaratively defines AWS, GCP, and Azure infrastructure using HCL.
Test Spec File
Naming convention for test files (.spec.ts or .test.ts) automatically discovered by test runners.
Testing Library
Library family for testing components from the user's perspective, focusing on behavior over implementation.
text-overflow
CSS property truncating overflowing text with an ellipsis. Used with overflow:hidden and white-space:nowrap.
Think-Aloud Protocol
Usability technique where users verbalize thoughts while interacting with a UI. Highly effective for finding issues.
Three Pillars of Observability
Logs, Metrics, and Traces — the three pillars providing full observability into system behavior.
Throttle
Limiting a function to execute at most once per time interval. Used for scroll or resize events.
Timezone Handling
Best practice storing dates in UTC and converting to local time on the frontend with Intl.DateTimeFormat or dayjs.
Timing Attack
Side-channel attack inferring secrets from processing time differences. Mitigated with constant-time comparison.
TLS Handshake
Key exchange and authentication process before encrypted communication starts. The start of every HTTPS connection.
Toast Notification
Temporary notification appearing at screen edge and auto-dismissing. Unobtrusive feedback.
Token
String used for auth. Typically sent as a Bearer token in headers.
Token (LLM)
Minimal text unit processed by LLMs, roughly a word or subword. Cost is calculated per token.
Token Rotation
Issuing a new refresh token on each use to detect and prevent reuse of leaked tokens.
Tokenizer
Tool splitting text into tokens for LLM processing. BPE and SentencePiece are widely used algorithms.
Tooltip
Explanatory text appearing on hover. Combine with aria-label for full accessibility support.
TOTP
Time-based One-Time Password. Generates a 6-digit code every 30 seconds seeded from the current time.
Touch Target
Minimum tappable size on mobile (Google recommends 48x48dp). Undersized targets increase user errors.
Transaction Isolation Level
Levels defining how isolated DB transactions are from each other. Ranges from READ COMMITTED to SERIALIZABLE.
Transfer Learning
Transferring knowledge from a pre-trained model to a new task. Achieves high accuracy with limited data.
Transformer
Deep learning architecture built on attention. Foundation of GPT, BERT, and most modern AI models.
Transpile
Translating code from one language version to another (e.g., TS to JS) so browsers can run it.
Tree Shaking
Build optimization removing unused code from bundles. Works effectively with ES module libraries.
Trie
Tree data structure sharing string prefixes. Used for autocomplete search and routing implementations.
tRPC
Framework for building type-safe APIs using only TypeScript, sharing types between client and server.
TTI
Time to Interactive. Time until the page is fully interactive. Long JS blocking worsens TTI.
TTL
Time to Live. Seconds a cache or DNS record stays valid. Too short increases load; too long stales data.
TTS (Time to Second)
Family of Web Vitals metrics (TTFB, FCP, TTI, LCP) measuring how quickly a page becomes usable.
Turbopack
Rust-based next-gen bundler for Next.js by Vercel. Provides ultra-fast HMR as Webpack's successor.
Turborepo
Build system by Vercel optimizing parallel task execution and caching for monorepos.
Type Assertion
TypeScript as syntax forcing the type checker to accept a specific type. Overuse undermines type safety.
Type Hierarchy
Typographic design distinguishing headings, subheadings, body, and captions to communicate content importance.
Type Narrowing
TypeScript technique narrowing types with if statements, typeof guards, and type guard functions.
Type Scale
Systematic ratios for text sizes across headings, body, and captions. Often uses 1.25 or 1.618.
TypeScript
JavaScript with static typing. Catches errors before runtime, essential for large teams.
Technical Debt
Implied cost of additional rework caused by choosing an easy solution now instead of a better approach.
Telemetry
Automated communications process by which measurements are collected at remote points.
Tensor
Mathematical object represented as an array of components that are functions of the coordinates of a space.
TDD (Test Driven Development)
Software development process relying on very short development cycles for each new feature.
Throttle
Process used to regulate the rate at which an action is performed, such as event listeners.
Token Bucket
Algorithm used to control the amount of data that is injected into a network.
Traceability
The degree to which a relationship can be established between two or more products of the development process.
Transformation (AI)
Process of altering data in structure, format, or value for processing by AI models.
Transpilation
Type of source-to-source compilation that translates code from one language to another.
TEE (Trusted Execution Environment)
Secure area of a main processor that ensures sensitive data is stored, processed, and protected.
U Nhóm
UDP
Fast, connectionless protocol without delivery guarantees. Used for video streaming and DNS queries.
UI Component Library
Library providing reusable UI components like buttons, inputs, and modals. MUI, shadcn/ui, and Ant Design are examples.
UI Design Pattern
Reusable UI solution templates for recurring design problems. Covers navigation, forms, and data display.
Uncontrolled Component
React approach managing form values via ref and DOM directly instead of state. Suits simple forms.
Unit Test
Smallest test scope verifying individual functions or modules in isolation. Often written with Jest or Vitest.
Unix Timestamp
Seconds since Jan 1 1970. Timezone-agnostic format excellent for system interoperability.
Unvalidated Redirect
Implementation flaw using user-supplied URLs as redirect destinations. Listed in OWASP Top 10.
Upstash
Serverless Redis and Kafka over HTTP. Well-suited for caching in edge environments.
URL Encode
Converting characters to %XX format for URLs so they don't break network protocols.
URL State Management
Storing UI state like filters and pagination in URL query params so state is restored when sharing URLs.
Usability Testing
Core UX research method observing real users completing tasks to identify problems.
useCallback
React hook memoizing a function to prevent unnecessary child re-renders. Dependency array management is key.
useEffect
React hook handling side effects like API calls and subscriptions on mount and state changes.
useMemo
React hook caching expensive computation results. Recomputes only when dependencies change.
User Flow
Diagram mapping a user's step-by-step journey through an app toward a goal.
useRef
React hook holding a mutable value without triggering re-renders, also used to reference DOM elements.
useState
React's fundamental hook for adding state to functional components.
UTC
Coordinated Universal Time. The base timezone. Servers and databases should always store times in UTC.
UUID
128-bit Universally Unique Identifier. Can be generated randomly with extremely low collision risk.
UX Audit
Systematic evaluation of an existing product to identify improvements in usability, accessibility, and KPIs.
UX Research
Qualitative and quantitative studies understanding user behavior, needs, and motivations. Includes interviews and surveys.
UX Writing
Crafting UI text (buttons, errors, empty states) that guides users and communicates clearly.
Unidirectional Data Flow
Data modeling pattern where the updates only travel in a single direction.
Universal Design
Design of products and environments to be usable by all people, to the greatest extent possible.
Unpushed Commits
Commits that exist in a local repository but have not yet been uploaded to a remote server.
Upstream
Original repository from which a project was forked or the source of component dependencies.
V Nhóm
Value Proposition
Clear statement of unique value a product delivers. The foundation for UI and copywriting decisions.
Vector Database
Database for fast similarity search of high-dimensional embedding vectors. Pinecone and Qdrant are examples.
Viewport Meta Tag
<meta name='viewport'> tag telling mobile browsers to use the device width. Required for responsive design.
Virtual DOM
Lightweight JS representation of the real DOM. React diffs it to apply minimal actual DOM updates.
Visual Feedback
UI communicating action results: button highlights, loading indicators, and success/error messages.
Visual Hierarchy
Using size, color, contrast, and placement to communicate information importance and guide attention.
Visual Regression Testing
Comparing UI screenshots to detect unintended visual changes. Percy and Chromatic are popular tools.
ViT
Vision Transformer applying the Transformer architecture to images by treating patches as sequences.
Vite
Ultra-fast dev server and build tool based on native ES modules. Popular successor to CRA and Vue CLI.
Vitest
Fast unit test framework built on Vite with Jest-compatible API.
VPC
Virtual Private Cloud. Logically isolated network in the cloud with subnets, routing, and security groups.
Vue.js
Progressive JavaScript framework known for gentle learning curve. Popular for small to medium projects.
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WAL
Write-Ahead Log. Records changes before writing to DB files for crash recovery and replication.
Wayfinding
Navigation design helping users know where they are and how to reach their destination without getting lost.
WCAG
Web Content Accessibility Guidelines. International standard for making web content accessible.
Web Components
Browser-native component model consisting of Custom Elements, Shadow DOM, and HTML Templates.
Web Worker
API running JavaScript in a background thread separate from the main thread to prevent UI blocking.
WebAssembly
Binary format enabling code written in C++, Rust, etc. to run at near-native speed in browsers.
WebGL
JavaScript API for GPU-accelerated 3D graphics in browsers based on OpenGL ES. Foundation for Three.js.
Webhook
Mechanism where an app sends an automated HTTP request to another app when an event occurs.
Webhook Security
Verifying webhook payloads with HMAC-SHA256 signatures to confirm they come from the legitimate sender.
WebP
Modern image format by Google. Smaller than JPEG/PNG, supports transparency, greatly improves performance.
WebSocket
Protocol establishing full-duplex channels between browser and server. Used for chat and real-time apps.
WebSocket Protocol
Full-duplex protocol established by upgrading an HTTP connection. Uses ws:// or wss:// URL scheme.
Whisper
OpenAI's open-source automatic speech recognition model. Supports multiple languages with high accuracy.
Wireframe
Low-fidelity blueprint communicating page structure and layout without visual styling.
Worker Threads
Node.js module running CPU-intensive tasks in parallel threads separate from the main thread.
Web Vitals
Essential metrics (LCP, CLS, INP, etc.) defined by Google to measure the quality of user experience on the web.
Web Scraping Ethics
Principles and legal considerations to follow when programmatically extracting data from websites.
X Nhóm
XSS
Cross-Site Scripting. Major vulnerability injecting scripts into web pages. Prevented by escaping.
XState
JavaScript state machine and statechart library. Visualizes and manages complex UI state.
Y Nhóm
YAML
Human-readable data format using indentation. Heavily used in config files like Docker Compose.
Z Nhóm
Z-Pattern
Eye movement pattern reading a page in a Z-shape. Appears on banners and pages with sparse content.
Zero Trust
Security model trusting nothing by default, continuously verifying every access attempt.
Zero-Day
Unknown vulnerability that has no patch yet, or an attack exploiting such a vulnerability.
Zero-Shot Learning
LLM capability performing unseen tasks from prompt alone without any additional training.
Zod
TypeScript-first schema declaration and validation library providing both type inference and runtime validation.
Zustand
Lightweight React state management library with a simple API. Gaining popularity over Redux.
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.env
File for environment variables. Stores secrets like API keys. Never commit this to Git.
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