BitTorrent is a noncommercial protocol for sharing large files and filesets. It's super easy to use. BitTorrentDownloads are started just by clicking on small .torrent files or hyperlinks. Downloaders get pieces of the fileset from the original server, and from anyone else who is downloading. The more people there are downloading the same thing, the lower the burden on the central server, and the faster everyone's downloads get, due to sharing with each other. The more, the merrier!
Learn much more here:
http://wiki.etree.org/index.php?page=BitTorrent