The king of all exercises and the key to an overall balanced and muscular physique. The primary muscles used in deadlifts are the lower back and traps. Secondary muscles used are just about every other muscle in the body.
Developing the right technique is the key to building strength and muscle quickly as this is one of the most effective exercises. You must learn the proper technique to avoid injury - this exercise may seem as simple as picking the weight up from the floor for beginners but it's anything but easy.
With the bar on the ground stand at the bar with your feet a little narrower than shoulder width apart. Grip the bar a little wider than shoulder width apart. Keep the bar as close to your shins as possible and bend down as if you were about to sit in a chair. With your head up and your back straight drive up with your legs as you lift the bar until you are in a completely upright position.
DO NOT ROUND YOUR BACK!! Drive with your legs throughout the whole exercise while keeping your lower back straight to avoid injuring your lower back.
I strongly recommend adding deadlifts to your workout for the quickest strength and muscle gains.