Stepper motors operate differently from DC motors, which rotate when voltage is applied to their terminals. They have electromagnets arranged around the rotor. The electromagnets are energised to provide a precise, stepped, rotation.

Due to this design, the motor’s position is controlled, without a feedback device, and provides low-cost, dynamic motion, especially in low-speed applications. 

For higher performance, the motors can be fitted with an encoder (closed-loop control).