A popular file sharing service developed by Bram Cohen that prevents people from downloading constantly unless they are willing to share in the overall transmission load on the network. Released in the summer of 2001, BitTorrent is similar to KaZaA and other distributed swapping services where users download from other users and do not use a centralized directory as in the original Napster service. However, BitTorrent is also different than all of them because it makes every downloading user an uploading user.

Large Files Become Torrents
Instead of downloading an entire file, BitTorrent breaks a file into chunks and distributes them among several participating users. When you download a "torrent," you are also uploading it to another user. BitTorrent balances the load because broadband download and upload speeds are not the same. Users download files faster than they can upload them, which makes them less interested in sharing bandwidth to upload to someone else. BitTorrent ensures every user participates in uploading.

BitTorrent has become widely used for transferring huge program files as well as pirated movies. In 2004, one estimate placed BitTorrent files as a third of all Internet traffic. Although the specific amount for BitTorrent may vary, the combination of all file sharing applications in use account for a huge chunk of traffic. For more information, visit www.bittorrent.com. See peer-to-peer network, Napster and KaZaA.

File swapping systems have been architected in different ways as outlined in the following illustrations: