Computers are information processing machines. That means that you can use them to access and change information like numbers, text, pictures, and even music. Think of what you can do to modify a single sentence. Using the computer, it's easy to add, delete, or rearrange words. To change a sentence with your computer, though, first you have to get the sentence into your computer.
Input devices are used to put information in your computer. You type a sentence on your keyboard and it goes into the computer. You speak into a microphone and your computer records your words. You make funny faces at the video camera and your computer records every one of them. Even the mouse you are about to click to move on to the next section is an input device. So, when you are ready, click it!