.webm File — WebM Video

WebM is an open, royalty-free multimedia format developed by Google, based on the Matroska container. WebM files contain video encoded with VP8, VP9, or AV1 codecs paired with Vorbis or Opus audio. The format was specifically designed for web use, offering efficient compression, fast seeking, and built-in support for HTML5 video. VP9, the most commonly used WebM video codec, provides compression comparable to H.265/HEVC while being completely royalty-free. AV1, the next-generation codec, offers 30-50% better compression than VP9. WebM is the preferred video format for YouTube (which uses VP9 for most content and is transitioning to AV1), Wikipedia, and many web applications. The format supports alpha channel transparency in video, enabling composited video overlays in web pages. WebM is natively supported by Chrome, Firefox, Edge, and Opera, with Safari adding VP9 WebM support. The combination of open licensing, excellent compression, and broad browser support has made WebM essential for web video delivery. Google provides encoders (libvpx, libaom) and the ffmpeg project includes full WebM support.