Windows Media Video (WMV) is a file type which can contain video in one of several video compression formats developed by Microsoft. The original video compression format used in the file, also known as WMV, was originally designed for Internet streaming applications, as a competitor to Real Video. The other compression formats, such as WMV Screen and WMV Image, cater for specialized content. Through standardization from the Society of Motion Picture and Television Engineers (SMPTE), WMV9 has gained adoption for physical-delivery formats such as HD DVD and Blu-ray Disc. Though sometimes used interchangeably, note the distinction between Windows Media, the file type, and Windows Media Video, the video compression format. Windows Media the file type is a container (in the Advanced Systems Format) which can contain video in one of several different video compression format, only one of which is the Windows Media Video video compression format, alongside audio in an audio coding format.
The Matroska Multimedia Container is an open standard free container format, a file format that can hold an unlimited number of video, audio, picture, or subtitle tracks in one file. It is intended to serve as a universal format for storing common multimedia content, like movies or TV shows. Matroska is similar in concept to other containers like AVI, MP4, or Advanced Systems Format (ASF), but is entirely open in specification, with implementations consisting mostly of open source software. Matroska file extensions are .MKV for video (with subtitles and audio), .MK3D for stereoscopic video, .MKA for audio-only files, and .MKS for subtitles only.