How many types of Electric Motors you know?

An electric motor is a device that converts electrical power into mechanical energy. During this conversion, some input is lost as heat. The amount of loss depends on the type of energy source and how it is converted.
There are many different types of electric motors. They can be categorized by power source, construction, application and type of motion output. They are also referred to as permanent magnet, induction or wound-rotor motors.

Rotor: The rotor in an electric motor is made of a steel shaft with a magnetically-generated electromagnet at its center. The rotor may rotate forwards, backwards or sideways depending on how it is arranged.
Commutation: The commutator is a rotary electric switch that supplies alternating or direct current to the rotor winding as it spins. It consists of several sections with metal contacts named "brushes" that slide against each other as the rotor spins.
Power: The electric supply voltage to a motor is typically a three-phase AC system that ranges from 230 volts line-to-line for low-power motors (0.5 to 50 kilowatts) to about 15 kilovolts line-to-line for high-power motors (up to 10 megawatts).
Efficiency: The efficiency of an electric motor is dependent on how well it can control its power consumption. Using less energy is better for the environment and helps to reduce costs.
Durability: An electric motor contains fewer moving parts that increase its life. If designed and maintained properly, an electric motor can last for three years without major repairs.