MP3, is a file used for digital audio  formats. Mp3s use a  form of  data compression MP3s are the most common audio format for consumer audio storage.

Mp3 files were first developed in the early 1990s. In 1994 mp3 files first hit the internet and were available for Music downloads.

When Mp3 files were first available as music downloads the  ease of creating and sharing MP3s resulted in widespread copyright infringement. Major record companies argue that this free sharing of music reduces sales. They reacted by pursuing lawsuits against Napster the first free mp3 music download site  (which was eventually shut down) and eventually against individual users who engaged in file sharing.

Unauthorized MP3 free downloads and file sharing continues on next-generation peer-to-peer networks.  This is a continuing problem but more independent artists are find new way of giving away free mp3 downloads and still making money.