DC machines are electrical devices that convert direct current (DC) electrical energy into mechanical energy or vice versa. They consist of a rotor, stator, and commutator, which work together to produce motion. These machines are commonly used in applications like electric vehicles, cranes, and fans due to their ability to provide high starting torque and speed control. There are two main types of DC machines: DC motors and DC generators. DC motors convert electrical energy into mechanical energy, while DC generators do the opposite, converting mechanical energy into electrical energy. Both types are essential in various industries for their efficiency and reliability.