A torrent is the necessary file created when sharing data using the BitTorrent protocol. More and more organizations are using torrents to share files. When using one of the many BitTorrent clients you can opt to create a torrent from a file on your hard drive.
The .torrent file contains a great deal of information including the file names, sizes and the date created. Every .torrent file also contains an info hash which is unique to its file and differentiates the torrent from other similar ones.
In order for the .torrent file to function it also contains a tracker, which is a server that tracks live torrent files and statistics. When you locate and launch a torrent file in your client it locates all the other computers which have parts of the file and allows your client to download the file by choosing parts from all the other people sharing the data.