From LQWiki

Parallel port

An older style of computer connection, superceded by PS/2, USB and other types of connections.

In the real world, ports are places where boats come in to dock and offload and take on cargo and passengers. In the virtual world, the boats are things like printers, mice, keyboards, monitors, etc and the cargo is data.

You plug the device into the port, which looks like a rectangle with the top two corners lopped off and with a bunch of pins (on the plug) or a bunch of holes (on the port) The funny shape is so that the connection can only be plugged in one way, the right way. On the plug there are usually screws to tighten once it is plugged into the port- to insure of a secure and tight connection.

A parallel port is a two way street- data can come in (mouse, keyboard) or go out (monitor, printer)

There is a growing community using paralell ports and linux to control things such as coffee pots etc.

The only application that activley uses parralel ports today are printers and some scanners, but newer models are comming with USB etc connections aswell or exclusivly.