webm The WebM extension is an HTML5 standard for distributing and viewing videos over the web. WebM is primarily designed for use on the web using the HTML5 tags <video> </video>. Its design is based on the Matroska container, video compression in the WebM file format is often done with VP8-enabled technology. WebM is a high quality, open-source, standard video format which lets users play videos on the web. It is specifically catered for video playback on the web and in web browsers. A unique aspect about the WebM extension is that it adapts to various bandwidths, processing environments, and is used over a wide range of media playing devices. The audio compression technology used in the WebM file extension is known as the OGG Vorbis Compression.