Do I use P2P, NNTP AND HTTP Downloading?

I want to know what P2P downloading is. We are thinking of changing our ADSL account and the one we want to go for says that if the network is to "busy" or something like that then P2P downloading, HTTP downloading and NNTP traffic will be "managed."

What are these 3 and how are they used. I want to tell if we will use it often, cause we don't like being throttled.
Thanks