Answer: The rotor is the movable part of the motor. Rotors maybe contained within the stationary portion of the motor (the stator) or rotors maybe outside of the motor. Motors with rotors that envelop the stator are sometimes referred to as having "outer rotors." Most motors have a "shaft" that protrudes from the rotor used for the transfer of mechanical energy.

The stator as stated above is the stationary, non-moving, portion of the motor. The stator my have windings or permanent magnets to create the field that interacts with the rotor. The stator is generally enclosed in shell called the "housing."

Some motors have a rotor that has windings. Brushes are the contacts mounted on the stator or housing that are used to bring current to the rotor windings. Brushes are often made of a carbon composition. They are generally spring loaded and replaceable.

Commutation is the act of converting DC to AC, or AC to DC. In motors that use this type of mechanism, the "commutator" consists of the array of contacts that are on the rotor. The brushes bring electrical current to the commutator contacts.

A generator produces DC. An alternator produces AC.

In a generator or alternator, the armature is the winding in which a voltage is induced. The armature may be on the rotor or the stator depending on how the device is constructed.

In a generator or alternator, the field windings set up the magnetic field that is made to "cut" the windings on the armature. The field windings may be on the rotor or the stator.

A "universal motor," also called an "AC commutator motor," or a "AC series motor" is built such that it will operate with either an AC or DC power supply. Depending on the specific motor construction, this type of motor may overheat when operated on DC.