A USB printer port is a socket built into a printer as a way of connecting the printer to a computer. A USB plug is plugged into the port and then into a USB port on the computer, connnecting the devices. via a USB cord. This removes the need for a bulky printer cable connecting to a parallel port. It also means there is no problem connecting a printer to a computer that comes without a parallel port, such as most laptops.
USB, or Universal Serial Bus, is the standard connector for most devices that plug into a computer. Because USB uses a standard socket on the computer and one of three standard plugs on the device itself, most modern devices are certain to be connectable to a modern computer. It is technically possible for more than 100 USB devices to be connected to the same PC.
Traditionally, printers used a parallel port connection. This is a multi-pin plug and socket system which takes its name from the fact that the data transmitted through each pin is sent simultaneously, unlike earlier serial ports where only one pin was active at a time. The main disadvantages are that the plug is fairly clunky and most PCs only have one parallel port, while some new desktops and most portable computers do not have a parallel port.
Most new printers instead work through a USB printer port. This name is used simply for identifying the particular USB port being used, rather than it being a special design. The cable is usually a standard USB plug, known as type A, at the computer end, with a square USB plug, known as type B, at the printer end. While USB cables can power some devices directly from the PC, this usually isn't the case with a USB printer port.
In set-ups with an older printer that does not have a USB socket, and a computer which does not have a parallel port, an adaptor can be used. This is usually in the form of a cable which has a USB plug at one end and a 15-pin socket at the other. It's important to note this is a female socket rather than a male plug. This means a standard parallel cable is still needed, running from the printer to the adaptor. While this set-up works for most printers, it usually isn't suitable for some other devices that can be connected to a parallel port, such as a scanner.
In most cases, a printer connected via a USB printer port will be automatically recognized by the computer's operating system. If it isn't, a driver will have to be installed: this is a small piece of software that co-ordinates an operating system and a hardware device. If the operating system doesn't locate the driver automatically, it can usually be installed from a CD that comes with the printer, or downloaded from the manufacturer's Internet site.