The Deadlift

The Deadlift is the most important exercise next to the Squat because it works all your muscles with the heaviest weights possible. Deadlifts will also teach you to pick up an object with a straight back - this will prevent injuries like hernias which usually result from repeatedly lifting with a round lower back.

How to Deadlift.
I've found proper technique to be absolutely crucial for Deadlifting big weights and eliminating lower back pain. 

1. Stand with the bar above the center of your feet - your stance should be a bit more narrow than shoulder-width to give your arms room.
2. Grab the bar overhand so your arms are vertical to the floor.
3. Bend through your knees until your shins hit the bar which must remain above the middle of your feet. Shoulder-blades directly over the bar.
4. Lift your chest but don't squeeze your shoulder-blades like on Squats. Just put your shoulders back & down, head inline with rest of your spine.
5. Pull - keep the bar close to your body, roll it over your knees and thighs until your hips and knees are locked. Do not lean back at the top.

That is all there is to it. Lower the bar by pushing your hips back first, and then bend your knees once the bar reaches knee level (NOT before otherwise the bar will hit your knees).