An open source multimedia container format that holds multiple audio, video, photo and subtitle tracks. Software players for Windows, Mac, Linux and smartphones are available to play Matroska files. Named after the Russian "matroshka" nested dolls, Matroska files are often called "MKV files" because the .MKV extension is used for movies. Audio-only and subtitle-only files use the .MKA and .MKS extensions. Derived from the open source Multimedia Container Format (MCF) in 2002, Matroska uses a binary XML format known as Extended Binary Meta Language (EBML) rather than the binary format in MCF. For more information, visit www.matroska.org. See multimedia container, DivX and binary XML.