What Is BitTorrent?

Pieces, peers and hashes

BitTorrent is a peer-to-peer protocol for distributing large files. The content is split into fixed-size pieces, each with its own hash, and those pieces are traded among everyone downloading the same content. A peer downloads a piece, checks it against its hash, then offers it to others. The more people download, the more upload capacity the group has, which is the reverse of a traditional server that slows down as demand grows.

The rest of the vocabulary follows from that design. A torrent file or magnet link describes the content. Trackers and the distributed hash table help peers find each other. The group sharing one torrent is a swarm, made up of seeders and leechers.

Legitimate traffic on the same protocol

BitTorrent is not a piracy tool by design. Game companies, open-source operating system projects and research institutions use it to move large files efficiently. Any monitoring setup has to allow for this, and a rights holder's own authorised distribution, including promotional material, should be on a whitelist agreed before enforcement starts so that it is never reported by mistake.

Why BitTorrent piracy has outlasted so many takedowns

The protocol has no centre. Index sites can be removed and trackers shut down, but the content keeps moving as long as peers hold it, and the DHT lets them find each other without any site at all. Index operators adapted as well: magnet links replaced stored files, mirror domains replace seized ones, and private communities keep the first copies away from public view.

BitTorrent piracy is less visible than it once was, as streaming sites have taken much of the casual audience. It remains an important source layer, though, because many copies that end up on streaming sites and cyberlockers start life as torrent releases.

Which parts of a BitTorrent ecosystem can be acted on

Enforcement works where someone is responsible:

• index and search sites that list the torrents, through notices to the site, its hosting and its infrastructure providers;
• search engines, by delisting the pages that lead users to those indexes;
• persistent seeders on seedboxes and dedicated servers, through their hosting providers;
• subscribers, in countries with notice schemes or court-ordered disclosure, where procedures differ widely.

Evidence in all of these cases rests on the same core: the infohash, verified pieces of the protected work and timestamped observations. A content protection programme normally pairs torrent monitoring with the streaming and file-hosting channels that the same releases go on to feed.