What is this car part called?

The pictured car part is called a brake rotor. It is a vital part of a vehicle's braking system and is responsible for converting the friction from the brake pads into a braking force that slows or stops the vehicle. Brake rotors are usually made of cast iron or steel and are mounted on the wheel hubs. When the brake pedal is pressed, the brake pads press against the brake rotor, creating friction that slows or stops the vehicle.