Can someone explain to me the whole sorority rush/bid/pledge mabob?

i don't get this whole sorority/fraternity thing but a lot of my friends are talking about their plans to rush (which i ume, means trying out) for sororities. I plan to attend ucsb and I think i would be interested in "trying out" (whatever terminology belongs there) for one of their asian-american sororities. can someone explain to me how these things work? LOL. i know the fall is a long ways to come, but im curious at the moment :). do they basically just haze you (atleast that's what i hear from people)? thanks for any info :D.