In the BitTorrent file distribution system, a torrent file or METAINFO 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, sizes, folder structure, 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.
In a nutshell, a torrent file is like a table of contents in that it facilitates the efficient lookup of information (but doesn’t contain the information itself). A torrent file gives addresses for computers around the world which can send parts of the requested file. Torrent files themselves and the method of using torrent files have been created to ease the load on central servers, as instead of sending a file to for request, it can crowd-source the bandwidth needed for the file transfer. With help of torrents, one can download small parts of the original file from computers that already have it. These “peers” allow for downloading of the file in addition to, or in place of, the primary server.