How do you put data to the (1)? How do you get (2) out? Here we will introduce the (3)which enable (4) and computer to communicate. Input devices translate (5) and program (6) that people understand into a form that computers can (7). Output devices do the opposite. They translate computer-processed (8) into a form that people can comprehend. There are several ways to get new information or (9) into a computer. To serve different application purposes, input devices can be classified into four types: letter input devices, pointing input devices, imaging and video input (10), and audio input devices.