An actuator is an electromechanical device that converts electrical energy into mechanical energy in order to provide a physical action, either linear or rotary. Electrical signals are sent to an actuator, which then controls a mechanical component or system. By doing so, actuators can trigger automatic control of functions, such as opening/closing valves in the piping system, starting/stopping a motor, changing the speed of a motor or adjusting the temperature of a room. In robotics, actuators can be used to control robotic arms or legs, allowing the robotic device to move around.