The advantage of precision control, open-loop control of the motor, self contained braking, and the absence of brushes, makes the stepper motor a convenient choice for a variety of specialized applications. Printers and plotters, disk drives, robots, computer numerical control machines, and other precision machines are common examples where the stepper motor is used extensively.
The operation of a stepper motor can be explained by considering a series of electromagnets arranged in a circle to encapsulate a rotor made up of a magnetic material. When these solenoids, or electromagnets, are energized in sequence, the magneto motive force developed in them interacts with the rotor and causes it to re-align to the magnetic field, thereby causing it to rotate in a clockwise or counterclockwise direction. You can control the angular displacement of the motor by simply switching these electromagnets on or off in a fixed pattern for the desired motion of the motor.