Fullscreen API
Required for video players, presentations, games, and immersive experiences. Understanding the security restrictions (user gesture required, no cross-origin iframes by default) prevents fullscreen request failures.
What It Defines
Defines Element.requestFullscreen() and Document.exitFullscreen() for entering and exiting fullscreen mode. Includes the :fullscreen CSS pseudo-class, fullscreenchange/fullscreenerror events, and the fullscreenEnabled property.
Canonical (Normative)
Convenient (Practical)
Maintains the living standards for the web platform: HTML, DOM, Fetch, URL, Streams, and more. These are continuously updated living documents, not versioned snapshots.
Related Specs
The spec behind every HTML page, form, and browser API. The canonical reference for how browsers actually parse and process HTML.
Required for video players, video calls, and live streaming UIs that need to stay visible while multitasking. Document PiP extends this to custom player controls, chat overlays, and productivity widgets.