Napster was developped in May 1999 by Shawn Fanning for people to share music files over the his school's network. The program turned into a real phenomena and turned MP3 into a standard digutal music format.
Napster came under legal trouble and it's central server was shut down by court order due to copyrighted material being shared on it's network.
The program was bought by Bertelsmann AG (BMG) and is undergoing a new commercial stragety.
Napster's concept has inspired a whole generation of file-sharing applications.