How do disc brakes slow a vehicle?

Disc brakes slow a vehicle by using a caliper to squeeze brake pads against both sides of a spinning metal disc called a rotor, which is attached to the wheel. The friction converts the vehicle's kinetic energy into heat, slowing the wheel. Hydraulic pressure from the brake fluid, created when you press the pedal, forces the caliper to clamp. Drum brakes, an older design still used on some rear wheels, press shoes outward against a drum instead. Disc brakes dissipate heat better. Understanding friction-based braking is key brake-system content.