An automotive style disc brake. A disc mounts to the hub, and the brake pads grip the disc (instead of the wheel rim). Disc brakes come in mechanical (cable actuated) and hydraulic (brake fluid or mineral oil in small brakelines).
In brakes, the rotor, the part which revolves, and against which brake linings are pressed during braking.
The disc is one of the more important parts in a carâ€™s braking system.