Single-phase induction electric motors have only one phase, being powered by a single-phase alternating current and are generally very often applied when a smaller motor with smaller power is required.
The induction motors employ a rotor called the squirrel cage, which has a special device for starting and the main advantage considered to it, is its low cost for small powers. This special device consists of a starting winding attached to the stator.
Single-phase motors, because they only have a single power supply, do not have a rotating field, like polyphase motors, they do have a pulsating magnetic field. This factor will allow the impedance so that they have conjugate to the starting, since in the rotor, if they induce magnetic fields aligned with the field of the stator.
The process in which only the stator is connected to the mains supply, affects the main factor that distinguishes the induction motor, where the rotor is not fed from the external side, and the chains that circulate freely in it, are electromagnetically induced by the stator, comes hence the origin of its induction motor name.