Brakes are a key component of vehicles whose main purpose is to slow or stop the vehicle. They work by reducing the kinetic energy of the vehicle through friction, where the brake pads or calipers are pressed against the surface of the brake disc or drum. This process creates resistance that slows the rotation of the wheels and allows the vehicle to stop safely. Brakes are also important for controlling speed when driving downhill and for maintaining stability and control of the vehicle in the event of an emergency stop.