So what's in the actual torrent file? It varies based on the client used to make it, but generally it contains an 'announce' section which is the address of the tracker you're using, and a big huge list of all the pieces of the file you wanna download.

This latter approach is to increase the overall 'health' (availability) of the torrent. The protocol can work one of two ways, either you'll download random pieces of the file, or you'll be downloading the rarest pieces first. Now pretend you're a computer downloading a file, using Bittorrent. Pieces that fail hash checks are discarded. The file itself, legalthing.iso, is cryptographically hashed so that each person who reads the torrent file and begins downloading legalthing.iso can check each piece against the hash, and ensure they're not downloading a piece that's been modified from the original. The torrent file can either point directly to your computer (and you'd be acting as the seed) or the torrent file can point to a 'tracker', which is a server that connects 'seeds' (users with the whole legalthing.iso file already) and 'peers' (users who are actively downloading the file).

So you create a 'torrent' file, which describes legalthing.iso, and you distribute the torrent file through a website, or any other way you like. Welcome to the wonderful world of Torrents! There are a few pieces that comprise the Bittorrent protocol: you have your file, legalthing.iso and you want to distribute it to as many people as possible.

How to use torrent files