TORRENTS: When you download a (.) torrent file, you are essentially downloading a small file that contains information on the larger files you want to download. The torrent file tells your torrent client the names of the files being shared, a URL for the tracker, and more.
Your torrent client then calculates a hash code, which is a unique code that only your torrent has—kind of like an ISBN or catalog number. From there, it can use that code to find others uploading those files, so you can download from them.