In the BitTorrent file distribution system, a torrent file or meta-info file is a computer file that contains metadata about files and folders to be distributed, and usually also a list of the network locations of trackers, which are computers that help participants in the system find each other and form efficient distribution groups called swarms. A torrent file does not contain the content to be distributed; it only contains information about those files, such as their names, folder structure, sizes, and cryptographic hash values for verifying file integrity. The term torrent may refer either to the metadata file or to the files downloaded, depending on the context.
This feature is very commonly used by open source projects offering software downloads. Web seeds allow smart selection and simultaneous use of mirror sites, P2P or HTTP(S), by the client. Doing so reducing the load on the project's servers while maximizing download speed. MirrorBrain [de] automatically generates torrents with web seeds.
Private torrents are to be used with a private tracker. Such a tracker restricts access to torrents it tracks by checking the peer's IP, refusing to provide a peer list if the IP is unknown. The peer itself is usually registered to the tracker via a gated online community; the private tracker typically also keep statistics of data transfer for use in the community.
Decentralized methods like DHT, PeX, LSD are disabled to maintain the centralized control. A private torrent can be manually edited to remove the private flag, but doing so will change the info-hash (deterministically), forming a separate \"swarm\" of peers. On the other hand, changing the tracker list will not change the hash. The flag does not offer true privacy, instead operating as a gentlemen's agreement. 1e1e36bf2d