ParallelExplanationA D-shaped, 25-pin connector connects to the parallel port (DB-25 port) of a computer. Parallel connectors are used with older devices, such as dot matrix printers.Serial ports have nine pins and are used with serial devices (e.g., barcode scanners). VGA ports have 15 pins ( three rows of five pins) and are used with VGA monitors. USB ports are rectangular in shape and are typically not used with older devices.