Brake pads are a key brake part because they are the component that contacts and applies pressure and friction to a vehicle's brake rotors. Brake pads convert the kinetic energy of the vehicle to thermal energy through friction. Two brake pads are contained in the brake caliper, with their friction surfaces facing the rotor. When the brakes are hydraulically applied, the caliper clamps or squeezes the two pads together onto the spinning rotor to slow and stop the vehicle.
In disc brakes, there are usually two brake pads per disc rotor. These are held in place and actuated by a caliper affixed to the wheel hub or suspension upright. Disc brakes offer better stopping performance as compared to drum brakes. They provide better resistance to brake fade caused by the overheating of brake pads and are also able to recover quickly from immersion. Unlike a drum brake, the disc brake has no self-servo effect—the braking force is always proportional to the pressure applied on the braking pedal lever. In most of the vehicles, a warning light or message will appear on the dashboard when its time to change the brake pads.