This is the file extension for an MPEG I, Layer II audio file. This audio format had some popularity in the a.b.s.m. newsgroup pre '96, before MP3 started becoming more commonplace. MP2 is also the format of the audio portion of MPEG 1 video, as used in VideoCDs. Just like the great Vinyl vs CD debate, there are some people who believe MP2s sound better than MP3s. While they are rare to see, if you come across an MP2 on Napster - you can play it. Windows Media Player, Sonique and Winamp all have support for MP2 files.