[1] The BitTorrent protocol coordinates segmented file transfer among peers connected in a swarm.
A BitTorrent client enables a user to exchange data as a peer in one or more swarms.
[2] Many BitTorrent programs are open-source software; others are freeware, adware or shareware.
Opera 12, a web browser, can also transfer files via BitTorrent.
In 2013 Thunder Networking Technologies publicly revealed that some of their employees surreptitiously distributed a Trojan horse with certain releases of Xunlei, the company's BitTorrent-ready download manager.