Brakes come in four main types. Knowing the different types will help you understand what you are looking at. There are two types of service brakes (the ones that stop your car) and then almost all vehicles also have an emergency brake and anti-lock brakes.
Disc Brakes: This type of brake consists of a brake rotor which is attached directly to the wheel. Pressure from the master cylinder causes a caliper to squeeze the brake pads on either side of the rotor causing friction. This then causes the vehicle to decrease speed and stop.
Drum Brakes: This type of brake has a drum attached to the inside of the wheel and when the brake pedal is pushed it causes pressure that pushes two brake shoes against the brake drum. Again, friction is created and the vehicle slows to a stop.
Emergency Brakes: This break is also known as a parking brake. It is a secondary brake that is independent from the service brake. Coming in many different forms (a stick between the seats, a third pedal, a push button, or a handle near the steering wheel, etc.) almost all of them are powered cables which apply pressure to the wheels. Their general use is to keep a vehicle stationary but in an emergency (hence the name) can be used if the service brakes fail.
Anti-Lock Brakes (ABS): This type of break is found on most newer vehicles. If the service brakes are applied suddenly, ABS stops the wheel from locking up. This will also keep the tires from skidding. Most of the time, ABS is most beneficial on wet and slippery roads.



