If you're wondering what deadlifts are, and want to see the strongest man on the planet (as of 2009, anyway) deadlift 1,008 lb (about 3 minutes in), watch THIS:
If you're a nerd like me and want to know the physics of how things work in addition to doing things with perfect form, watch THIS:
The deadlift works the posterior chain: the low back, the glutes, and the hamstrings. Of course, I'll never be anywhere close to deadlifting (you lift a dead weight from the floor, hence the name), but I'm gonna do my best to eventually get to a place where I can lift twice my weight - that's a 1 rep max, of course. For now,I'll stick with the lighter weights and make sure my form is perfect.