A desktop computer is a personal computer that fits on or under a desk. They usually consist of a monitor, keyboard, mouse and either a horizontal or vertical (tower) form factor. Unlike a laptop, which is portable, a desktop computer is meant to stay at one location.
Desktop computer overview
Below is a picture of a computer with each of the main components that help make up a computer. In the picture, you can see the Desktop computer, Flat-panel display, Speakers, Keyboard, and Mouse. We've also labeled each of the input devices and output devices.