USB cables let you attach accessories to your computer.

Just about any computer that you buy today comes with one or more Universal Serial Bus connectors. These USB connectors let you attach mice, printers and other accessories to your computer quickly and easily. The operating system supports USB as well, so the installation of the device drivers is quick and easy, too. Compared to other ways of connecting devices to your computer (including parallel ports, serial ports and special cards that you install inside the computer's case), USB devices are incredibly simple.

­In this article, we'll look at USB ports from both a user and a technical standpoint. You'll learn why the USB system is so flexible and how it's able to support so many devices so easily -- it's truly an amazing system.

Anyone who has been around computers for a while knows the problem that the Universal Serial Bus is trying to solve -- in the past, connecting devices to computers has been a real headache.

  • Printers connected to parallel printer ports, and most computers only came with one. Things like external storage media, which need a high-speed connection into the computer, would use the parallel port as well, often with limited success and not much speed.
  • Modems used the serial port, but so did some printers and a variety of odd things like personal digital assistants (PDAs) and digital cameras. Most computers had at most two serial ports, and they were very slow in most cases.
  • Devices that needed faster connections came with their own cards, which had to fit in a card slot inside the computer's case. Unfortunately, the number of card slots is limited and some of the cards are difficult to install.

The goal of USB is to end all of these headaches. The Universal Serial Bus gives you a single, standardized, easy-to-use way to connect up to 127 devices to a computer.

Just about every peripheral made now comes in a USB version. A sample list of USB devices that you can buy today includes:

In the next section, we'll look at the USB cables and connectors that allow your computer to communicate with these devices.