BitTorrent (Wikipedia entry) is a data sharing protocol that changes the file download paradigm from a one-to-one model to a many-to-many-model (peer-to-peer). This allows extremely large files to be shared without stressing a single download source point. It also means that if you download a file, you will also be allowing others to download fragments of the file from you too for some period of time. You can choose to terminate sharing the file with others after you have a complete file. But, this is considered a breach of netiquette.

One of the easiest ways to use BitTorrent is to use... Azureus

The Java-based Open Source applications can run on pretty much anything: Linux, Mac OS, Windows.

I've found it useful to download DVD ISO files for the various Linux distros I like to try out as new versions become available. Many Linux distros provide the multi-CD ISO files via ftp but only provide the DVD ISO file via BitTorrent.