Electrical motor in general is an electro-mechanical device that converts energy from electrical domain to mechanical domain.A synchronous electric motor is an AC motor in which, at steady state,[1] the rotation of the shaft is synchronized with the frequency of the supply current; the rotation period is exactly equal to an integral number of AC cycles. Synchronous motors contain multiphase AC electromagnets on the stator of the motor that create a magnetic field which rotates in time with the oscillations of the line current. The rotor with permanent magnets or electromagnets turns in step with the stator field at the same rate and as a result, provides the second synchronized rotating magnet field of any AC motor. A synchronous motor is termed doubly fed if it is supplied with independently excited multiphase AC electromagnets on both the rotor and stator Based on the type of input we have classified it into single phase and 3 phase motors. Synchronous motors are more widely used in industrial 
Main Features:
Some of the main features of synchronous motor are as follows:-
1. Synchronous motors are inherently not self starting.
2. They require some external means to bring their speed close to synchronous speed to before they are synchronized.
3. The speed of operation of is in synchronism with the supply frequency.
4. At supply frequency is constant they behave as constant speed motor irrespective of load condition.
5. This motor has the unique characteristics of operating under any electrical power factor. This makes it used in electrical for power factor improvement.
Application Of Synchronous Motors:
1. As synchronous motor is capable of operating under either leading and lagging power factor, it can be used for power factor improvement. A synchronous motor under no-load have leading power factor. It is used in power system in place of static capacitors.
2. Synchronous motor is used where high power at low speed required. Such as rolling mills, chippers, mixers, pumps, pumps, compressor etc.