Lap top computers Laptop computers are lightweight mobile PCs with a thin screen. They are often called notebook computers because of their small size, Laptops can operate on batteries, so you can take them anywhere. Unlike dcsktops, laptops com-bine the CPU, screen , and keyboard in a single case. The screen folds down onto the keyboard when not use Desktop computers Desktop computers are designed for use at a desk or table They are Typically larger and more powerful than other types of personal computers. Desktop computers are made up of separate components. The main component, called the system unit, is usually a rectangular case that sits on or underneath a desk Other components, such as the monitor,mouse , and keyboard, connect to the system , unit.