File extensions

The styling language for the web. Paired with HTML it controls colour, layout, animations, and media queries.

The source of a web page. A browser renders it; a text editor shows you the markup underneath.

Source for the language that runs the web — in browsers and on servers (Node.js, Bun, Deno). Central to interactive UIs and modern tooling.

A single-file web page: HTML, images, and CSS bundled as a MIME multipart message. Born with Internet Explorer and still common in Chinese enterprise software and some government portals.

A binary instruction format that runs near-native in browsers. Compiled from Rust / C / C++ for heavy computation or fast web apps.

The single-file web archive produced when Safari saves a page on macOS or iOS. Internally a binary plist bundling HTML, images, CSS, and JS.