A Group
A/B Test
Randomly showing two variants to users to statistically determine which improves KPIs.
a11y
Numeronym for Accessibility. Designing the web so everyone, including people with disabilities, can use it.
AbortController
Browser API for cancelling async operations like fetch. Used to abort requests on component unmount.
Above the Fold
Visible area without scrolling. Place the most important content and CTAs here for maximum impact.
Accessibility Audit
Inspection finding accessibility issues. Combines automated tools like axe and Lighthouse with manual testing.
Accessibility Statement
Page disclosing a site's accessibility conformance level and contact for issues. Legally required in some regions.
Accessibility Tree
Tree derived from the DOM passed to assistive technologies like screen readers. ARIA attributes appear here.
ACID
Atomicity, Consistency, Isolation, Durability. Fundamental properties for reliable database transactions.
ACID Guarantee
DB guarantee maintaining consistency even on mid-transaction failure, via Atomicity, Consistency, Isolation, Durability.
Adaptive Loading
Web strategy dynamically adjusting resources and features based on device CPU, memory, and network speed.
AES
Advanced Encryption Standard. Symmetric encryption standard. AES-256 is recommended for high security.
Affordance
Design cue that intuitively communicates how to interact with an element, like button depth or underlined links.
AI Agent
LLM-based system autonomously planning and executing tasks using tools. Often uses ReAct pattern.
AI Alignment
Research ensuring AI systems' goals and behaviors align with human intentions and values.
AI Safety
Research field ensuring AI systems behave safely without unintended harmful actions. Includes interpretability.
Amazon Aurora
AWS managed RDBMS compatible with MySQL and PostgreSQL. Claimed up to 5x faster than standard MySQL.
Amazon RDS
AWS managed relational database service offering MySQL, PostgreSQL, MariaDB, and more.
Amazon S3
AWS object storage with virtually unlimited scale and 11 nines of durability.
AMQP
Advanced Message Queuing Protocol. Wire-level protocol used by RabbitMQ and other message brokers.
Animation Performance
Achieving smooth 60fps animations by using only transform and opacity to leverage GPU composite layers.
Ansible
Agentless IaC and configuration management tool. Automates server setup with YAML Playbooks.
Apache Flink
Distributed stream processing framework for real-time event handling. Commonly paired with Kafka.
Apache Kafka
High-throughput distributed event streaming platform. Used for log ingestion and event-driven microservices.
Apache Spark
Distributed computing framework for large-scale parallel data processing. Used for batch jobs and ML.
API
Application Programming Interface. Specification for how software components communicate, often via REST and JSON over HTTP.
API Gateway
Entry point routing client requests to backend microservices. Also handles auth and rate limiting.
API Key
String token authenticating API access. Role scoping, rotation, and revocation management are critical.
API Mocking
Dummy server returning fake responses during development and testing instead of real backends. MSW is popular.
API Versioning
Strategy for evolving APIs while maintaining backward compatibility via URL path, headers, or query params.
App Router
Next.js 13+ routing system leveraging React Server Components with nested layouts.
ARIA
W3C spec supplementing HTML with roles, states, and properties for screen readers.
aria-live
ARIA attribute notifying screen readers of dynamic content changes. polite queues; assertive interrupts.
Aspect Ratio
Width-to-height ratio. The CSS aspect-ratio property maintains ratios like 16:9 in responsive layouts.
AST
Abstract Syntax Tree. Tree representation of source code used by linters, Babel, and code analysis tools.
Astro
Web framework shipping zero JS by default using Island Architecture for extreme performance.
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
UI methodology structuring components into 5 layers: Atoms, Molecules, Organisms, Templates, Pages.
Attack Surface
Total of all possible entry points for attackers. Reducing API endpoints and open ports minimizes it.
Attention Mechanism
Core Transformer technology computing relevance weights between all tokens in a sequence.
Auth Rate Limiting
Limiting login attempts to prevent brute force and credential stuffing attacks.
Auto Scaling
Automatically adjusting server count based on load. AWS Auto Scaling and K8s HPA are prime examples.
AutoML
Automating model selection, hyperparameter search, and feature engineering in machine learning.
Autoprefixer
PostCSS plugin automatically adding vendor prefixes to CSS. Ensures cross-browser compatibility.
Availability Zone
Physically isolated data center groups in AWS. Distributing across AZs achieves high availability.
AWS Fargate
AWS serverless container engine requiring no server management. Used with ECS or EKS.
AWS Lambda
AWS serverless computing service running functions on events. Pay-per-execution pricing model.
AWS Step Functions
AWS serverless workflow orchestrator. Visually builds complex business flows combining Lambda and other services.
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 Group
B2B SaaS
Software as a Service for businesses. Multi-tenancy, role management, and SSO are common requirements.
Backpressure
Flow control mechanism signaling upstream to slow down when downstream processing falls behind.
Backpropagation
Algorithm propagating prediction error backward through a neural network to update weights.
Barrel File
index.ts re-exporting multiple modules to shorten import paths.
BASE
Basically Available, Soft state, Eventual consistency. Consistency model common in NoSQL, contrasting ACID.
Base64
Encoding that represents binary data using 64 ASCII characters. Used for Data URIs. Not encryption.
Batch Normalization
Normalizing activations within a mini-batch to stabilize and accelerate deep neural network training.
bcrypt
Password hashing algorithm with a cost factor to slow brute-force attacks. The recommended default for passwords.
BEM
Block, Element, Modifier. CSS naming convention using block__element--modifier to avoid style collisions.
BERT
Google's bidirectional Transformer for NLU tasks like classification and question answering.
BGP
Border Gateway Protocol. Exchanges routing information between Autonomous Systems on the internet.
BigQuery
Google Cloud's serverless data warehouse. Analyzes petabyte-scale data with SQL in near-real-time.
Biome
Rust-based linter and formatter for JS/TS aiming to replace ESLint and Prettier in one tool.
Blob Storage
Object storage for unstructured data like images and videos. AWS S3 and Azure Blob Storage are examples.
Bloom Filter
Probabilistic data structure for fast, memory-efficient membership checks. Used to reduce cache misses.
Blue-Green Deployment
Deployment strategy running two environments simultaneously, swapping traffic for zero downtime.
Blur Placeholder
Showing a blurred low-res image while the full version loads. Implemented via Next.js blurDataURL.
Brand Guidelines
Rules defining logo, colors, fonts, and tone to maintain brand consistency. Foundation of a design system.
Breakpoint
CSS threshold where layout changes based on screen width. Defined with @media queries.
Browser DevTools
Built-in browser debugging tools. Includes Elements, Console, Network, and Performance panels.
Brute Force Attack
Attack trying all possible combinations to crack passwords or keys. Mitigated with rate limiting and lockout.
Bug Bounty
Program paying security researchers for responsibly disclosing vulnerabilities. HackerOne facilitates this.
Build Tool
Tools transforming source code for production. Includes Vite, Webpack, Rollup, and esbuild.
Bulkhead Pattern
Resilience pattern isolating resource pools so failures in one don't cascade to others.
Bun
All-in-one fast JavaScript runtime, package manager, and bundler.
Bundle Size Analysis
Visualizing JS bundle contents to find unnecessary libraries and duplicates. webpack-bundle-analyzer is common.
Bundler (バンドラー)
Tool that combines multiple JS/CSS modules into optimized files. Webpack, Vite, and Rollup are common examples.
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 Group
Cache (キャッシュ)
Temporarily storing fetched data to avoid re-fetching. Fundamental for improving performance.
Cache Busting
Adding a hash to file names to force browser cache invalidation. Used as main.abc123.js.
Cache Strategy
Patterns like Cache-Aside, Write-Through, and Write-Behind for reading and writing cache.
Canary Release
Releasing a new version to a small subset of users first, then gradually rolling out to everyone.
Canvas API
HTML5 API for 2D graphics rendering in the browser. Used for games, charts, and image processing.
CAP Theorem
Theorem stating distributed systems can guarantee at most 2 of Consistency, Availability, Partition Tolerance.
Card Sorting
UX research method observing how users categorize information. Informs information architecture.
CDN
Content Delivery Network. Distributed servers that deliver static assets quickly based on user location.
CDN Cache Invalidation
Purging or updating cached CDN content. Critical step to prevent stale content after deployments.
Certificate Pinning
Hardcoding a specific TLS certificate in the client. Strengthens resistance to MITM attacks.
Chain of Thought
Prompt technique having LLMs show reasoning steps. Improves accuracy on complex problems.
Chunked Transfer Encoding
HTTP encoding sending responses in chunks. Used when the total content size is unknown upfront.
Chunking
Splitting long documents into smaller pieces for LLM context windows in RAG pipelines.
Chunking (UX)
UX technique grouping information into smaller chunks to reduce cognitive load. Multi-step forms are an example.
CI/CD
Continuous Integration / Continuous Deployment. Automates testing and deployment of code changes.
Circuit Breaker
Resilience pattern that temporarily blocks requests to a failing service to prevent overload.
Circuit Breaker States
Three-state machine of circuit breaker: Closed (normal), Open (blocking), Half-Open (testing recovery).
clamp()
CSS function taking min, preferred, and max values. Perfect for responsive font sizes without media queries.
CLI
Command Line Interface. UI navigated entirely by typing text commands in a terminal.
ClickHouse
Column-oriented OLAP database. Extremely fast for log analysis and time-series aggregation queries.
Clickjacking
Attack overlaying invisible iframes to hijack clicks. Prevented with X-Frame-Options header.
Client Component
Next.js App Router component marked 'use client', executing JavaScript in the browser.
CLIP
OpenAI model aligning images and text in the same embedding space. Used for image search.
CLS
Cumulative Layout Shift. Measures unexpected layout shifts during load. One of the Core Web Vitals.
CNAME
DNS record type aliasing one domain name to another. Commonly used for CDN and custom domains.
CNN
Convolutional Neural Network. Specialized for image recognition using convolution and pooling layers.
CockroachDB
Distributed SQL database combining horizontal scalability with ACID compliance and geo-distribution.
Code Injection
Broad attack category where malicious code is injected into an application. SQLi and XSS are subtypes.
Code Splitting
Splitting JS bundles into smaller chunks loaded on demand to reduce initial load time.
Cognitive Load
Mental effort required to understand and use a UI. Good design minimizes cognitive load.
Cold Start
Initial latency when a serverless function starts after being idle. A key drawback of serverless.
Color Blindness Accessibility
Design practice ensuring color-blind users can distinguish information using shape, icons, and text alongside color.
Color Scheme
CSS mechanism to switch light/dark themes based on OS settings using the prefers-color-scheme media query.
Column Store
Database storing data column-by-column. Fast for aggregation queries and ideal for OLAP workloads.
Composable
Vue 3 function that encapsulates reusable logic, equivalent to React custom hooks.
Compound Component
React pattern where parent and child components share state via Context for flexible composition.
Computed Property
Reactive value automatically derived and cached from other data. Core to Vue and MobX.
Computer Vision
AI field extracting information from images/video. Covers object detection, segmentation, and face recognition.
Concurrent Mode
React 18 mode allowing interruptible rendering to maintain UI responsiveness during heavy work.
Connection Pool
Reusing database connections to reduce connection overhead and manage concurrency efficiently.
Connection String
URL-format string containing DB host, port, and credentials. Always managed via environment variables.
Consistent Hashing
Hash algorithm minimizing data redistribution when nodes are added or removed in distributed systems.
Constitutional AI
Anthropic's technique defining explicit principles for AI behavior, enabling self-improvement via those rules.
Container Orchestration
Automating container deployment, scaling, networking, and health checks. Kubernetes is the de facto standard.
Container Query
CSS feature applying styles based on parent container size, enabling component-level responsiveness.
Container Registry
Repository for storing, managing, and distributing Docker images. DockerHub, ECR, and GCR are common.
containerd
Container runtime managing container lifecycle inside Docker. The default runtime for Kubernetes.
Content Compression
Reducing transfer size by compressing text resources with Brotli or gzip.
Content Negotiation
HTTP mechanism where client and server negotiate response format via Accept headers.
Content-First Design
Approach defining content structure before UI design. Evaluates designs with real copy, not placeholder text.
Context API
React built-in for passing data deep into component trees without prop drilling.
Context Window
Maximum tokens an LLM can process at once. Larger windows handle more context but increase cost.
Contextual Inquiry
Field research method observing and interviewing users in their actual work environment to uncover latent needs.
Continuous Delivery
Practice of keeping code always releasable to production. Deployment is triggered manually.
Contrast (コントラスト比)
Difference in luminance between foreground and background. WCAG recommends 4.5:1 for normal text.
Controlled Component
React pattern where form inputs are controlled by state and onChange handlers, keeping data and UI in sync.
Conventional Commits
Commit message convention using prefixes like feat, fix, and chore. Enables automated semantic releases.
Conversion Rate
Percentage of visitors completing a goal action like purchase or signup. A primary UX success metric.
CORS
Cross-Origin Resource Sharing. Browser security mechanism for API calls from different origins. Requires backend headers.
CORS Preflight
Browser's OPTIONS request before a cross-origin call to verify permission from the server.
CORS Security
Setting CORS headers to a whitelist rather than wildcard to protect APIs from unauthorized origins.
Cosine Similarity
Metric measuring directional similarity between vectors (-1 to 1). Used to compare embedding vectors.
Covering Index
Index containing all columns needed by a query, avoiding access to the main table rows entirely.
CPU Profiling
Measuring which parts of a program consume CPU resources to identify performance bottlenecks.
CQRS
Pattern separating read (Query) and write (Command) models for scalability and clarity.
Create React App
Facebook's React scaffolding tool. Migration to Vite is now recommended for new projects.
Credential Stuffing
Attack trying leaked email/password pairs on other services. MFA and password managers are the main defenses.
Critical CSS
Optimization extracting above-the-fold CSS and inlining it to eliminate render-blocking.
Cron
Unix job scheduler. Automates recurring tasks like batch jobs using time expressions in crontab.
CronJob (K8s)
Kubernetes resource managing scheduled batch jobs using the same cron schedule syntax as Unix.
Cross-Entropy Loss
Loss function measuring divergence between predicted and true probability distributions. Widely used in classification.
CSAT
Customer Satisfaction Score. Measures satisfaction with a specific interaction on a 1-5 scale.
CSP
Content Security Policy. HTTP header that prevents XSS by restricting script sources and inline execution.
CSR
Client-Side Rendering. JavaScript renders HTML inside the browser. Core of SPAs, but creates initial load delay.
CSRF
Cross-Site Request Forgery. Attack forcing a user to execute unwanted actions. Prevented with anti-CSRF tokens.
CSS Animation
CSS feature using @keyframes and animation properties to animate HTML elements without JavaScript.
CSS Custom Property
CSS variables defined with -- prefix (e.g. --color) for reusable values across stylesheets.
CSS Grid
CSS 2D layout system. Define rows and columns to create complex layouts with minimal code.
CSS Mixin
Reusable style blocks defined with @mixin and included with @include in Sass/SCSS.
CSS Modules
Scoping CSS class names to components by generating unique names at build time.
CSS Subgrid
CSS feature allowing grid children to inherit parent grid tracks for precise alignment.
CSS-in-JS
Writing CSS inside JavaScript. Emotion and styled-components are popular examples.
CSV
Comma-Separated Values. Tabular data separated by commas. Extensively used for data export/import.
CTA
Call to Action. Button or link driving user action. Placement, copy, and color affect conversion.
CVE
Common Vulnerabilities and Exposures. Unique IDs (CVE-YYYY-NNNNN) for publicly known vulnerabilities.
Cypress
JavaScript E2E testing framework with an intuitive API for browser-based testing.
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 Group
DaemonSet
Kubernetes resource ensuring one Pod per node. Used for log collectors and monitoring agents.
DALL·E
OpenAI's model generating high-quality images from text prompts. Based on Diffusion Model architecture.
Dark Mode
Dark background UI theme. Reduces eye strain and saves battery on OLED screens.
DAST
Dynamic Application Security Testing. Scanning a running application from outside for vulnerabilities.
Data Augmentation
Artificially expanding training data with transformations like rotation and cropping to improve generalization.
Data Fetching Patterns
Strategies for when and where to fetch data: CSR, SSR, SSG, ISR. Core to Next.js architecture.
Data Lake
Large-scale storage architecture holding raw data in its native format for diverse future analysis.
Data Masking
Replacing sensitive production data with fake data for safe use in development and test environments.
Data URI
Inline embedding format for Base64-encoded images in HTML/CSS, reducing HTTP requests.
Data Warehouse
Centralized repository of structured data optimized for analytics and reporting. Redshift and BigQuery are examples.
data-* Attribute
Custom HTML attribute attaching metadata to elements. Accessible in JavaScript via the dataset API.
Database Cursor
DB pointer mechanism for processing large result sets row by row without loading everything into memory.
Database Index
Data structure speeding up queries on specific columns. B-tree is common; trades off write performance.
Database Sharding
Horizontally splitting data across multiple DB nodes for scale-out at the cost of design complexity.
DB Migration
Version-controlling schema changes alongside code. Flyway and Prisma Migrate are popular tools.
DB Transaction
Grouping SQL operations so all succeed or all roll back together, guaranteeing ACID properties.
DDD
Domain-Driven Design. Centers software around the business domain using Entities, VOs, and Aggregates.
DDoS
Distributed Denial of Service. Overwhelming a server with traffic to make it unavailable.
Dead Letter Queue
Queue storing messages that failed processing. Essential for debugging and reprocessing failures.
Debounce
Technique to execute a function only after a pause in continuous events. Prevents excessive API calls.
Declarative UI
UI paradigm where you describe what to show; the framework handles DOM updates. React and Vue use this.
Deep Link
URL that directly opens a specific screen in an app or website. Uses custom schemes or Universal Links.
Defense in Depth
Layering multiple security controls so that breaking one layer doesn't compromise the whole system.
Deferred Loading
Loading off-screen images or scripts only when needed. Implemented with loading='lazy' or Intersection Observer.
Deno
JavaScript/TypeScript runtime redesigned by Node.js creator. Native TS support and secure by default.
Dependency Graph
Directed graph representing module dependencies. Used to detect circular deps and optimize bundles.
Dependency Scanning
Automated checking of dependencies for known vulnerabilities. Dependabot and Snyk are popular tools.
Deploy Preview
Auto-generated staging environment per PR or branch for review. Provided by Vercel and Netlify.
Deployment Strategy
Methods like blue-green, canary, and rolling for releasing new versions with minimal downtime.
Design Critique
Structured process for reviewing designs based on goals, users, and principles rather than personal preference.
Design Debt
Accumulated inconsistencies from quick fixes and non-standard patterns. Requires periodic design audits to resolve.
Design Handoff
Process of transferring design specs from designer to engineer. Typically done via Figma or Zeplin.
Design Sprint
Google's 5-day framework for idea validation: Define, Sketch, Decide, Prototype, and Test.
Design System
Shared foundation of tokens, components, and guidelines. Ensures consistency and speeds up development.
Design Token
Variables for design values like colors and spacing. Keeps design and code consistent across teams.
Desktop-First
Design approach starting from large screens and scaling down. Mobile-First is now the recommended alternative.
DevOps
Culture and practices integrating Dev and Ops for faster, more reliable software delivery.
DHCP
Protocol automatically assigning IP addresses to devices joining a network.
DI (依存性の注入)
Dependency Injection. Pattern where dependencies are passed from outside, making components easily testable.
DI Container
Framework feature managing dependency injection. Provided by NestJS and Spring for large-app structuring.
Dialog / Modal
Overlay UI demanding user attention above main content. Requires aria-modal for accessibility.
Diffusion Model
Generative model iteratively denoising data. Stable Diffusion and DALL·E use this for image generation.
Directory Traversal
Attack using ../ sequences to access files outside the web root. Prevented by sanitizing file paths.
Distributed Lock
Mutual exclusion for distributed processes. Often implemented with Redis to prevent simultaneous updates.
Distributed Tracing
Visualizing request flows across microservices. Tools include Jaeger, Zipkin, and OpenTelemetry.
DKIM
Email authentication adding a digital signature to verify the sending domain's legitimacy.
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 Group
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.
F Group
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.
G Group
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.
H Group
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.
I Group
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.
J Group
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.
K Group
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.
L Group
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.
M Group
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 Group
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 Group
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.
P Group
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.
Q Group
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 Group
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.
S Group
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 Group
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 Group
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 Group
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.
W Group
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 Group
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 Group
YAML
Human-readable data format using indentation. Heavily used in config files like Docker Compose.
Z Group
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.
Other Other Terms
.env
File for environment variables. Stores secrets like API keys. Never commit this to Git.
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