what does lsd stand for and do?

i see lsd here and there about install and stuff but i can't seem to find out what it means and what i does. can anybody give me a clue?

LSD=Limited Slip Differential
and here is a great site that explains it all
http://auto.howstuffworks.com/differential8.htm

yeah, LSD trannys dont let one wheel sit while the other one burns out or anything like they, the two wheels move as one as opposed to the earlier. I think the type-R s have these... i want one lol

V T E C H, you do realize that you have spelled vtec wrong. There is no H.