Unlike drum brakes, where expanding shoes make contact with drums and the
resulting friction slows the car, disc brakes use a caliper that grips a steel
Frisbee-like disc located inside the wheel.
They are far more efficient than drum brakes, which are prone to fade when used
heavily (going down a mountain, for example).
Ventilated discs have ventilation holes that help keep them cool and therefore
even less prone to fading.