Bit Torrent - how does it work?

Can someone give a brief explanation about how bit torrent works: I have played around with the orginal, Burst and now Azureus (which seems much better). I started using it because I think it is a great idea, but was initially dissapointed by the download rates, until I followed was the rather counter-intuitive instructions of the Azureus website: basically, to limit to quite low levels the number of uploads, downloads and the upload bandwidth in line with my connection speed (600/100). Previously I had everything cranked to the max. After making the changes, the rates were so bloody high I am now thinking of upgrading my connection because I now think I could actually use all that badwidth.

But why does ramping down the settings make it work faster?

 

http://www.bittorrent.com/introduction.html