Each I/O device has a cable with a plug having several pins for plugging into a socket called port. A port is an interface is generally provided at the back of a computer. A port provides a direct link with the computer’s common electrical bus.
A serial port provides a connection for plugging a peripheral device with one data line that carry one bit at a time and additional lines to carry control signals.
A parallel port provides a connection for transmitting fast flow of large amount of data. Parallel ports allow 8 bits data at a time over a cable with eight separate data lines.
Next, learn about Computer bus and its types.