What is sweep picking guitar?

Question:i can play welcome home by coheed and cambria but it has at the intro your suppose to sweep pick, how do you do it and what it is can you explain it to me?

Best Answer - Chosen by Asker: i can play welcome home by coheed and cambria but it has at the intro your suppose to sweep pick, how do you do it and what it is can you explain it to me?

its hard to do
http://www.ultimate-guitar.tv/guitar_les... i learned from the video