FastTrack is a peer-to-peer (P2P) protocol, used by the Kazaa (and variants, Grokster and iMesh) file sharing programs. The file sharing application Morpheus originally used this network, but was later banished from it because of licensing disputes.
In 2003, FastTrack was the most popular file sharing network, being mainly used for the exchange of music mp3 files. Popular features of FastTrack are the ability to resume interrupted downloads and to simultaneously download segments of one file from multiple peers. Also, the search for a certain keyword is optimal: if the search is not stopped or timed out, FastTrack finds a source for the search if one exists.
The network had approximately 2.4 million concurrent users in 2003. It is estimated that the total number of users was greater than that of Napster at its peak.