An induction motor which connects with a 3-stage supply called 3-phase induction motor. Example enthusiasts,blowers, cranes,traction .It really is a ac electric motor. The primary drawback of DC motors may be the existence of commutator and brushes, which require regular maintenance and we can’t use DC electric motor in explosive and dirty three phase ac induction motor china environment. But induction motors are cheaper,rugged,lighter,smaller,require less maintenance and may use in filthy and explosive environment. Slide s is the imp factor in this 
There are 2 types of IM.
Squirrel cage IM
Slip ring IM
There are many 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 speed control technique of induction engine is important
Pole changing
Stator voltage control
V/f control
Slip power recovery
Rotor resistance control