A torrent is a constantly moving file over a large network. typically pirated movies, torrents work by people downloading a small beginning file, and then using a program (ie: transmission) to finish it. this program works by downloading the parts that you don't have from other people doing the same thing, and uploading the parts that others need. most torrent's contents are illegal. the current fine for having a copyrighted movie (most torrents) is up to $250,000 and/or up to 5 years in jail.
They didn't have the movie I wanted at blockbuster, so I downloaded the torrent.