An actuator is a device that produces a motion by converting energy and signals going into the system. The motion it produces can be either rotary or linear. Linear actuators, as the name implies, produce linear motion. This means that linear actuators can move forward or backwards on a set linear plane – a set distance they can travel in either direction before they must stop. Rotary actuators on the other hand produce rotary motion, meaning that the actuator revolves on a circular plane. Unlike linear actuators, rotary actuators are not restricted by a set path and can rotate in the same direction for any amount of time.