There may also be ports for sound and video input and output. Most PC computers come with Parallel, Serial, USB and now even FireWire, among others. The most common use for parallel ports is for connecting printers. Other peripherals like backup drives may also connect to a parallel port. The parallel port of any computer is usually located on the back panel of a desktop computer.
Most desktop computers come with just one parallel port.
You can hook two devices up to one parallel port using a pass through adapter. However, both devices cannot be used at the same time. There may be more than one USB port on your computer, and they are used for connecting devices to your computer. A USB connection allows for faster transfer of information between your computer and any device. Adding a scanner, digital camera or other gadget becomes easier and transfer rates of data become quicker than a parallel port connection.