Matroska (styled Matroška) is a project to create a container format that can hold an unlimited number of video, audio, picture, or subtitle tracks in one file.

[5] The project was announced on 6 December 2002[6] as a fork of the Multimedia Container Format (MCF), after disagreements between MCF lead developer Lasse Kärkkäinen and soon-to-be Matroska founder Steve Lhomme about the use of the Extensible Binary Meta Language (EBML) instead of a binary format.

[7] This coincided with a 6-month coding break by the MCF's lead developer for his military service, during which most of the community quickly migrated to the new project.

The logo writes it as "Matroška"; the letter š, an "s" with a caron over it, represents the "sh" sound (/ʂ/) in various languages.

[14] Software supporting Matroska include all ffmpeg/libav-based ones,[18] including, notably, mplayer, mpv, VLC, Foobar2000, Media Player Classic-HC, BS.player, Google Chrome, Mozilla Firefox, Blender, Kdenlive, Handbrake, MKVToolNix as well as YouTube (which uses WebM extensively),[19] and OBS Studio.