BitTorrent is an open source peer-to-peer file protocol for sharing large software and media files. It is a well established protocol which accounts for a significant proportion of internet traffic.
Over the years BitTorrent has received a considerable amount of bad press, mainly because the protocol is seen as a convenient way of facilitating mass illegal downloads of music, movies, games and software. Consequently, it is disliked by some content producers and industry and trade groups such as the Recording Industry Association of America (RIAA). However, the protocol also plays an important role in the legal distribution of software and files.
For example, many Linux companies rely on BitTorrent as a key method of distributing their software, relieving the bandwidth burden on their servers. Downloads get faster when there are lots of users downloading and sharing at once, which has meant that BitTorrent is very popular when a new version of a Linux distribution is released. Even with many simultaneous downloads, the upload burden on the central server remains quite small, since each new downloader introduces new upload capacity.
http://www.linuxlinks.com/portal/news/article.php?story=20090525115011604