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WCAG (Web Content Accessibility Guidelines)
The international standard for web accessibility, published by the W3C. The most-cited target is WCAG 2.1 AA — a checklist of testable rules covering color contrast, keyboard navigation, alt text, focus indicators, and more. Achieving AA is the practical bar for “accessible” in most legal and corporate contexts.
See also: Accessibility (a11y)
Webhook
An HTTP request a service sends to your URL when something happens, instead of you asking. “Pay attention to my endpoint; I’ll send you a POST when a customer pays.” Stripe, GitHub, and many SaaS tools use webhooks heavily. You usually need to verify the signature on incoming webhooks to make sure they’re really from the claimed sender.
See also: Webhooks
Webpack
A JavaScript bundler — takes your source files (and their imports) and produces a small number of optimized output files. The standard for most of the 2010s. Now largely replaced for new projects by Vite, Turbopack (Next.js), esbuild, and Rollup. You may still encounter it in older codebases.
See also: Build
WebSocket
A persistent, two-way connection between a client and a server over a single TCP connection. Unlike HTTP (request → response), either side can send a message at any time. Used for chat, live updates, multiplayer games, collaborative editing. Supabase has WebSocket-based “realtime” subscriptions for tables.
See also: WebSockets
Whitespace
Spaces, tabs, newlines. Mostly ignored by HTML and most programming languages. Mostly. (Python and YAML care a lot about indentation.) Critical for human readability of code.
Worker (Web Worker, Service Worker)
A JavaScript script that runs in a separate thread from the main UI thread, so it can do heavy work without freezing the page. Web Workers run general background code. Service Workers sit between the page and the network — letting you build PWAs, offline support, push notifications.
See also: PWA
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