This is the software publisher's description.
BitTorrent is a peer-to-peer protocol designed to transfer files. Users connect directly to send and receive portions of a file, while a central tracker co-ordinates the action of all peers and manages connections without knowledge of the contents of the files being distributed.
With BitTorrent, users upload at the same time they download, so network bandwidth is managed as efficiently as possible.
BitTorrent is designed to work better than other file-transfer protocols as the number of people interested in a certain file increases.
Mac OS X and Linux (v7) releaaes also available from the BitTorrent download page. This beta version is Windows only.