A servo motor is a rotary actuator or linear actuator that allows for a precise control in terms of angular position, acceleration and velocity, capabilities that a regular motor does not have. It makes use of a regular motor and pairs it with a sensor for position feedback. The controller is the most sophisticated part of the servo motor,often a dedicated module designed specifically for use with servo motor.
Servo motor is not a specific class of motor although the term servo motor is often used to refer to a motor suitable for use in a closed-loop controlled system.
Servo motor is widely used in applications such as robotics,CNC machinery,Plastic machinery or automated manufacturing.