A drum brake is a type of braking system commonly used in vehicles. It consists of a cylindrical drum that rotates with the wheel and brake shoes that press against the inner surface of the drum to create friction. This friction slows down or stops the vehicle when the driver applies the brakes. Drum brakes are often found on the rear wheels of many cars and trucks, as they are generally more cost-effective and provide adequate stopping power for lighter loads. However, they can be less efficient than disc brakes in high-performance situations due to heat buildup during prolonged use.