BitTorrent is a protocol currently used as the most prevalent method of peer to peer file sharing. It accounts for between 27-55% of all internet traffic.(1) BitTorrent is also the primary protocol used in internet piracy, allowing for copyrighted materials to be distributed quickly and efficiently to large numbers of users without the need for a central file storing database.

BitTorrent works by creating a metafile called a torrent that points to another file on the computer. This metafile serves as a guide for other computers to use to download the file onto their computers. This original file holder is known as a seed. A user downloading this file from the seed is known as a leech. The innovation of BitTorrent comes in the ability for leeches to download the file from each other without having yet finished the file. Rather than the sequential start to finish downloading of most protocols, BitTorrent assigns random sections of the file to be downloaded out of sequence by each leech, leaving each of the leechers with a different section of the file, which they can then download from each other. This reduces bandwidth problems for the seed by spreading out the data transfer among many computers. When a leech has a complete copy of the file, they too become a seed allowing even more leechers to gain access to the complete file. This decentralized method of downloading has proven highly effective and greatly contributed to the success of BitTorrent, though it has some disadvantages. A high number of leechers with low numbers of seeds can result in slow downloading and file unavailability, especially in older torrents as the seeds delete the metafile and stop sharing the original file.

The major controversy in BitTorrent downloads is the high number of pirated files that are being transferred using the protocol. As BitTorrent is a protocol rather than a network or a program the original creator of the BitTorrent protocol, Bram Cohen, has no control over the files being transferred. The major source of these pirated files come from Torrent Trackers, which are sites that monitor and track the health (seed to leech ratio) and availability of torrents being shared. One of the most prevalent of these is the Sweden based tracker The Pirate Bay which provides access to a vast number of pirate torrents. The Pirate Bay has come under attack numerous times by law enforcement agencies attempting to protect the copyrights of the files being shared on the tracker, but The Pirate Bay is still currently active.