MP4 is an abbreviation that can mean MPEG-4 Part 14 or MPEG-4 AVC. It is a file format that was first released in 1998 and is used for video files. MP4 is classified as a container file format as it can hold multiple media elements in a single file.
Media elements that make up a standard MP4 file include audio, video, still images and subtitles. The MPEG portion of the file name refers to an organization called the Motion Pictures Expert Group. This organization is responsible for establishing digital audio and video standards for the multimedia industry. As of 2015, the MP4 format is supported on various video player programs, such as Media Player Classic and VLC Media Player.