- An input device transfers information from the outside world into the computer. Sensors are input devices because they measure different conditions.
- Computers will process the information entered from different input devices using a control program.
- A control program will respond by controlling devices called actuators:
| Actuator | Action Produced | |
| Bulb |  |
Lights up an area. |
| Motor |  |
Rotates a shaft. |
| Buzzer |  |
Makes a beeping sound. |
| Heater |  |
Produces heat. |
| LCD Display |  |
Displays a graphic. |
An interface (sometimes called a control box) is usually used to connect many input devices and actuators to a computer.