An induction electric motor or 3 phase induction motor is an AC electric motor in which the electric current in the rotor had a need to produce torque is obtained by electromagnetic induction from the magnetic field of the stator Three Phase Motor winding
An induction electric motor which connects with a 3-phase supply called 3-phase induction motor. Example fans,blowers, cranes,traction .It really is a ac motor. The main drawback of DC motors is the existence of commutator and brushes, which require frequent maintenance and we can’t use DC motor in explosive and filthy environment. But induction motors are cheaper,rugged,lighter,smaller,require much less maintenance and will use in dirty 
and explosive environment. Slide s is the imp aspect in this type of motor.
There are 2 types of IM.
Squirrel cage IM
Slip ring IM
There are numerous starting and braking condition.
Important starting methods are
Star-delta starter
Auto transformer starter
Ac voltage controller starter
Rotor resistance starter
Important braking methods are
Regenerative braking
Plugging or reverse voltage braking
Dynamic braking
But one thing velocity control technique of induction motor is important
Pole changing
Stator voltage control
V/f control
Slip power recovery
Rotor resistance control