BitTorrent

(networking)A popular, distributed form of peer-to-peerfile sharing that enables a client program to fetchdifferent parts of a file (a "torrent") from different sourcesin parallel. The system is designed to encourage users tomake downloaded data available for others to upload. This isaided by a scheme for exchanging unique identifiers, commonlystored in ".torrent" files. A downloader who does not servedata to others is called a "leech". A "seed" is a computerthat has a complete copy of a file, possibly the original.

The bittorrent.com site claims there are over 100 millionusers as of 2007-03-24.

Most of the data is copyright material like films orcommercial software.

http://www.bittorrent.com/what-is-bittorrent.

BitTorrent

A popular protocol for sharing large files over the Internet, developed by Bram Cohen and released in 2001. In addition to Cohen's software, other BitTorrent client programs are available for all major platforms. There is no centralized server. Each downloading user becomes a source for another user who wants the same file. The BitTorrent client balances the load on the computer, because download speeds are faster than upload speeds.

Widely used for transferring pirated movies and software, BitTorrent, along with other file sharing systems, accounted for more than half of Internet traffic after the turn of the century. Since then, however, movie streaming from Netflix, YouTube and other legal sources became extremely popular, and BitTorrent traffic dropped dramatically.

Torrents
BitTorrent breaks large files into smaller ones. A "torrent" is a file of meta-data that describes the files and the servers that keep track of the BitTorrent peers that have the parts of the file. In practice, a file itself is also called a torrent.

Users Share the Load (Leechers and Seeds)
A "seed" is a BitTorrent client that has the file. A "leecher" is a BitTorrent client in the process of downloading, and a leecher thus becomes a seed for someone else. However, a "leech" refers to people who exit BitTorrent after downloading, thus preventing seeding to others. For more information, visit www.bittorrent.com.

File sharing systems have been architected in different ways as outlined in the following illustrations. See peer-to-peer network, Napster and KaZaA.