[USB] is an [Acronym] for __U__niversal __S__erial __B__us, which is a method of attaching peripherals to a computer. For example, USB mice, keyboards, scanners, printers and digital cameras are all common. USB provides power from the host computer, allows devices to be "chained", so that instead of having a mess of cables into the back of your computer, you could theoretically have your printer plugged into the computer, your scanner plugged into the printer, keyboard into scanner, and camera and/or mouse into the keyboard. 

  

 See HotPlug for notes on configuring devices that need extra set up at insertion time.