Torrent refers to Bit Torrent. It's a peer to peer file sharing
protocol. Which means you download from other people on the web, and at
the same (as soon as you have downloaded segments from the files you
want to retrieve !) you upload to other users. I could explain more
here, but there is a
good FAQ at filesoup.com. Though it's more geared towards warez, the general Bittorrent Overview is pretty good. There is also
Brian BT's FAQ that might be useful. Check the weblinks section to links to good BitTorrent clients.