what is port...?

*)    An interface on a computer to which you connect a device.

*) Internally there are several port for connecting                                 disk drive,display screen and key board.

*)  Externally personal computer have port for modem, printer and peripheral devices.

*) Almost all personal computers come with a serial RS-232C  port or RS-422  port for connecting a modem or mouse and a parallel port  for connecting a printer. 

*) The parallel port uses a 25-pin connector (type DB-25) and is used to connect printers.