In the electric motor, the moving part is the rotor which turns the shaft to deliver the mechanical power. The rotor usually has conductors laid into it which carry currents the interact with the magnetic field of the stator to generate the forces that turn the shaft. However, some rotors carry permanent magnets, and the stator holds the conductors.
The stationary part is the stator, usually has either windings or permanent magnets. The force between the two magnetic fields tend to rotate the motor shaft. The commutator switches power to the coils as the rotor turns, keeping the magnetic poles of the rotor from constant aligning with the magnetic poles of the stator field, so that the rotor never stops (like a compass needle does), as long as power is applied.
Motor field is including VCM, CDDVD-ROM,generator, electric motor, servo motor, micro shaped motor, motor, vibration motor, etc.