Browser Glossary

Browse 42 browser terms defined in plain English, from the cultural dictionary of computing.

42 Browser Terms

Clickjacking
An attack where a malicious site loads a target site in a transparent iframe positioned over a decoy UI, tricking users into clicking buttons on the hidden...
Content Security Policy
An HTTP response header that restricts which resources (scripts, styles, images, fonts) a browser is allowed to load for a page. A powerful defense against XSS...
Cookie Storage
A Cookie Storage is a development concept used to shape how software is built, executed, or maintained in real systems. Developers rely on it to make code...
CORS
CORS, or Cross-Origin Resource Sharing, is a browser security mechanism that controls how web pages from one domain can request resources from a different...
CORS Origin
The scheme + hostname + port combination that identifies where a web request originates from. CORS (Cross-Origin Resource Sharing) checks prevent JavaScript on...
CORS Preflight
An automatic OPTIONS request sent by the browser before a cross-origin request to check whether the server allows it. Triggered by non-simple methods (PUT,...
Critical Rendering Path
The sequence of steps the browser takes to convert HTML, CSS, and JavaScript into pixels on screen: parse HTML → build DOM → parse CSS → build CSSOM → combine...
DOM
DOM, or Document Object Model, is a programming interface that represents an HTML or XML document as a tree structure of objects, where each node corresponds...
Fetch API
The modern browser API for making HTTP requests, replacing the older XMLHttpRequest. Returns Promises, supports streaming responses, and integrates with...
HSTS
HTTP Strict Transport Security — a response header that tells browsers to only access the site over HTTPS for a specified duration. Prevents protocol downgrade...
IndexedDB
A low-level browser API for storing large amounts of structured data (including files and blobs) client-side. Unlike localStorage, it's asynchronous, supports...
IndexedDB
A low-level browser API for storing large amounts of structured data on the client side, including files and blobs. Unlike localStorage (which only stores...
Inspector
A development tool for examining and modifying the structure, styles, and behavior of a running application in real time. Browser DevTools' Element Inspector...
Intersection Observer
A browser API that asynchronously observes when an element enters or exits the viewport (or another element). Replaces expensive scroll event listeners for...
Layout Engine
The component of a web browser (or similar rendering system) responsible for computing the size and position of every element on screen by interpreting HTML,...
Local Storage
A browser API for storing key-value string data (up to ~5-10MB) that persists across sessions. Synchronous and blocks the main thread, so avoid storing large...
Mutation Observer
A browser API that watches for changes to the DOM tree — added/removed nodes, attribute changes, and text content modifications. Replaced the deprecated...
Preload
To force the browser or runtime to fetch a critical resource at high priority early in the page lifecycle, before the parser would naturally discover it. In...
Ready State
A property (readyState) on browser objects like XMLHttpRequest and Document that indicates the current phase of a lifecycle — for XHR: 0 (UNSENT) through 4...
Render Tree
The browser's internal representation that combines the DOM tree with computed CSS styles, containing only the visible elements (excluding display:none nodes...
Resize Observer
A browser API that reports changes to an element's dimensions. Unlike window resize events, ResizeObserver watches individual elements, enabling responsive...
Security Headers
HTTP response headers that instruct browsers to enable security features. Key headers: Content-Security-Policy (XSS prevention), Strict-Transport-Security...
Service Worker
A JavaScript proxy that runs in the background between your web app and the network. Intercepts fetch requests, enabling offline support, caching strategies...
Session Storage
A Web Storage API that provides per-origin, per-tab key-value storage in the browser; data persists across page reloads within the same tab but is cleared when...
Shadow DOM
A browser API that creates an encapsulated DOM subtree with its own scope for CSS and JavaScript. Styles inside the shadow DOM don't leak out, and external...
Wasm
Short for WebAssembly — a portable, low-level binary instruction format designed as a compilation target for languages like C, C++, Rust, and Go, executing in...
Web Animation API
A browser API that provides a JavaScript interface for creating and controlling animations that run on the compositor thread, offering programmatic access to...
Web Audio API
A high-level browser API for processing, synthesizing, and analyzing audio in real time by connecting AudioNode objects into a directed graph — from sources...
WebCodecs
A low-level browser API that provides direct access to hardware video and audio encoders and decoders, allowing frame-by-frame control over media processing...
Web Container
A browser-based runtime environment (pioneered by StackBlitz) that runs Node.js and its toolchain entirely inside the browser using WebAssembly and a virtual...
Web Crypto API
A browser-native JavaScript API (window.crypto.subtle) that exposes cryptographic primitives — hashing (SHA-256/384/512), HMAC, symmetric encryption...
WebGL
A JavaScript API that exposes an OpenGL ES-compatible interface for rendering hardware-accelerated 2D and 3D graphics within an HTML canvas element, giving web...
WebGPU
A modern browser API for GPU-accelerated graphics and general-purpose GPU computation, succeeding WebGL. Provides lower-level GPU access similar to...
WebHID
A browser API that allows web applications to communicate with Human Interface Devices (keyboards, gamepads, barcode scanners, FIDO authenticators) over USB or...
Web Push
A protocol (RFC 8030) and set of browser APIs that allow a server to send push notifications to a user's device through a push service, even when the web page...
WebRTC
Web Real-Time Communication — a set of browser APIs and protocols enabling peer-to-peer audio, video, and data streaming directly between browsers without...
Web Storage
A browser API providing two key-value stores — localStorage (persists until explicitly cleared) and sessionStorage (scoped to the browser tab's lifetime) —...
Web Worker
Web Worker is a JavaScript API that enables running scripts in background threads separate from the main execution thread of a web page, allowing...
WebXR
A browser API (succeeding WebVR) that provides access to virtual reality and augmented reality devices, handling session management, reference spaces, input...
Window
The global object in browser JavaScript that represents the browser tab or frame, providing access to the DOM (document), navigation (location), timers...
Worker
A background execution context — in browsers, a Web Worker runs JavaScript on a separate thread from the main UI thread, communicating via postMessage; in...
Worklet
A lightweight, low-latency script execution context in the browser that runs on a dedicated thread — used by the CSS Paint API (PaintWorklet), Audio Worklet...

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