What it includes:

Brake pads are replaced on disk brakes by removing the wheel, removing the caliper, replacing the pad, reseting the caliper, and resecuring the wheel.

Why you need it:

The only function more important then making a car go, is making it stop. Brakes serve tha purpose by creating friction between a rotor and a set of pads. As they are used, these pads wear down and require replacement, approximately every 40,000 miles. If you hear you're car squeeking every time you hit the brakes, you need to replace the pads.