Know how to use "fewer" and "less"? Find out.
A desktop mains powered unit into which a laptop or other portable computer can be connected via fixed connectors at the rear of the computer to provide quick and convenient connection of peripherals not normally used with a laptop. These can include power supply, expansion cards, additional storage, an external monitor, network card, CD-ROM, full-size keyboard, printer, and mouse. The alternative would require each of the above to be connected to the laptop individually.