The Arduino Motor Shield add-on PCB is based on the L298, which is a dual full-bridge driver designed to drive inductive loads such as relays, solenoids, DC and stepping motors. These items cannot be driven directly from the Arduino's ouput pins, so this module is essential for inventions that use motors, switches or relays. It lets you drive two DC motors with your Arduino board, controlling the speed and direction of each one independently. You can also measure the current consumption of each motor, among other features. The shield is TinkerKit compatible, which means you can quickly create projects by plugging TinkerKit modules to the board.