WebM is an open media file format designed for the web. Its files consist of video streams compressed with the VP8 video codec and audio streams compressed with the Vorbis audio codec. The file structure is based on the Matroska media container.
A key factor in the web’s success is that its core technologies such as HTML, HTTP, and TCP/IP are open and freely implementable. Though video is also now core to the web experience, there is unfortunately no open and free video format that is on par with the leading commercial choices. To that end, the WebM project started a broadly-backed community effort to develop an open web media format. It is an open-source project sponsored by google.
It was built for the web. By testing hundreds of thousands of videos with widely varying characteristics, they found that the VP8 video codec delivers high-quality video while efficiently adapting to varying processing and bandwidth conditions across a broad range of devices. VP8′s highly efficient bandwidth usage and lower storage requirements can help publishers recognize immediate cost savings. Also, the relative simplicity of VP8 makes it easy to integrate into existing environments and requires comparatively little manual tuning in the encoder to produce high-quality results.