BitTorrent is a peer-to-peer file sharing protocol used for distributing large amounts of data. BitTorrent is one of the most common protocols for transferring large files, and it has been estimated that it accounts for approximately 27-55% of all Internet traffic (depending on geographical location) as of February 2009.
BitTorrent protocol allows users to distribute large amounts of data without the heavy demands on their computers that would be needed for standard Internet hosting. A standard host's servers can easily be brought to a halt if high levels of simultaneous data flow are reached. The protocol works as an alternative data distribution method that makes even small computers (e.g. mobile phones) with low bandwidth capable of participating in large data transfers.
A BitTorrent tracker is a server that assists in the communication between peers using the BitTorrent protocol. It is also, in the absence of extensions to the original protocol, the only major critical point, as clients are required to communicate with the tracker to initiate downloads. Clients that have already begun downloading also communicate with the tracker periodically to negotiate with newer peers and provide statistics; however, after the initial reception of peer data, peer communication can continue without a tracker.