Gnutella Forums - What is an Ultapeer?

Stupid question I know.... But I am sharing files (average upload bandwidth used is 4-6Kbs).

During times of browsing my Gnucleus (to add more files to download, usually :-) ), I hit upon 'ultapeer'. I've checked the box in the options thingy, but have no idea what it is.

To be honest, I've not got a clue what gnutella is about, except that I'm getting a load of stuff I cant afford, or cant get hold of - I'm sharing my CD/DVD collection, so I feel I'm putting in as well as taking. But what is an ultapeer?? Hmm, must read through the source-code at some point; I assume its well commented/structured, lol, or is that pompus :-))

M