An actuator is a part that causes movement in a component. These can be any type of device that causes parts to move. They may be electric motors that throw or retract a bolt or a valve, for instance. On modular switches, these take the form of interfaces that allow the user to easily change the condition of the switch. They are oftentimes colored so that color codes can be used to differentiate between the different functions on a board full of switches. For example, the on switches on a board may have green actuators while the off switches might have red actuators. They come in various designs, such as rockers and pushbuttons, which can be selected for functionality and to fit the form and organizational scheme of the board to which they are affixed.