BitTorrent is a communication protocol for (P2P), which enables users to distribute data and s over the Internet in a decentralized manner.
To send or receive files, users use a BitTorrent client on their Internet-connected computer. A BitTorrent client is a computer program that implements the BitTorrent protocol. BitTorrent clients are available for a variety of computing platforms and operating systems, including an official client released by Rainberry, Inc. Popular clients include μTorrent, Xunlei Thunder, Transmission, qBittorrent, Vuze, Deluge, BitComet and Tixati. BitTorrent trackers provide a list of files available for transfer and allow the client to find peer users, known as "seeds", who may transfer the files.
Programmer Bram Cohen designed the protocol in April 2001, and released the first available version on 2 July 2001. On 15 May 2017, BitTorrent, Inc. (later renamed Rainberry, Inc.) released BitTorrent v2 protocol specification. libtorrent was updated to support the new version on 6 September 2020.
BitTorrent is one of the most common protocols for transferring large files, such as digital video files containing TV shows and video clips, or digital audio files containing songs. BitTorrent was responsible for 3.35% of all worldwide bandwidth—more than half of the 6% of total bandwidth dedicated to file sharing. In 2019, BitTorrent was a dominant file sharing protocol and generated a substantial amount of Internet traffic, with 2.46% of downstream, and 27.58% of upstream traffic. , BitTorrent had 15–27 million concurrent users at any time. , BitTorrent is utilized by 150 million active users. Based on this figure, the total number of monthly users may be estimated to more than a quarter of a billion (≈ 250 million).
The use of BitTorrent may sometimes be limited by Internet Service Providers (ISPs), on legal or copyright grounds. Users may choose to run seedboxes or virtual private networks (VPNs) to circumvent these restrictions.