An actuator's a mechanical device for moving or controlling a mechanism or system. An actuator typically's a mechanical device that takes energy, usually created by air, electricity, or liquid, and converts that into some kind of motion. Examples and applications Examples include: Mechanics - plasma actuators, pneumatic actuators, electric actuators, motors, hydraulic cylinders, linear actuators, etc. Human - muscles Biology - actuator domains found in P, F and V type ATPases In engineering,… (More on Actuator)