WebM is a video and audio container format released by Google, used with content encoded under the VP8 or VP9 codecs for video, and Vorbis and Opus for audio. It is a variant of Matroska, based on EBML.

Used in file types
  • .webm
This type may also appear as

This type isn't known to appear as any other mime types

Further reading
  1. Let's Solve the File Format Problem!