The name (or file extension) given to encoded sequences of MP3 files.
An .m3u file is a special type of metafile playlist that is used with MP3 files that have an .mp3 file extension. The .m3u file includes information about the location of the .m3u file on the computer and the properties of the file. An .m3u file is similar to the ASX playlist files.
When you create a playlist in some media players, like Winamp, the playlist file contains the extension M3U. Clicking an M3U file will bring up all of the songs in the playlist in your default audio player.