Brake discs are essential components of a vehicle's braking system. They are circular metal plates that work with brake pads to slow down or stop the vehicle when the driver presses the brake pedal. When the brake pads clamp down on the discs, friction is created, which helps to reduce the speed of the wheels. Typically made from materials like cast iron or carbon composite, brake discs come in various designs, including vented and slotted types. Regular maintenance is important, as worn or damaged brake discs can lead to decreased braking performance and safety issues while driving.