AVI - Audio Video Interleaved or Audio Video Interleave
Audio Video Interleaved is a multimedia file format that allows storage of both audio and video data with synchronous audio-video playback. It is a special case of the Resource Interchange File Format (RIFF). The file format was developed by Microsoft as part of its Video for Windows technology.
Unlike the standard video file formats there is no fixed codecs and formats for AVI file. These files also support multiple streaming of audio and video like the DVD file format. Due to its simple architecture, an AVI file can run on a wide variety of platforms including Windows, Mac, Linux, Unix etc.
AVI files can be opened with any popular video player, including Windows Media Player starting with version 7 and other media players like VLC Player, MPlayer and KMPlayer.