You download .torrent files, which identify the files you are looking to download and where to get information on who you can download them from. Using an application such as BitTorrent, uTorrent, etc, you can then use the .torrent file to locate and download those chosen files from a number of different peers. It can be a quick way to download large files and spread your work, whatever it may be. However, there are two main issues:

Problem #1: These are usually nameless individuals you're downloading from, not a trusted company. Thus, there is an increased risk of downloading malicious or infected files.

Problem #2: It's estimated that over 90% of all content on P2P and torrent networks is pirated, and therefore illegal to upload or download. Thus, you must investigate the legality of the download before accepting it.

Personally, I'd avoid using torrent networks unless there is a specific file you know is legal, you can't quickly download elsewhere, and you're prepared to scan it thoroughly before executing.

John