Parallel port
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In computing, a parallel port is a type of interface found on early computers for connecting peripherals. The name refers to the way the data is sent; parallel ports send multiple bits of data at once
A DB-25 connector often used for a parallel printer port on IBM PC compatible computers, with the printer icon.
Micro ribbon 36-pin female, such as on printers and on some computers, particularly industrial equipment and early (pre-1980s) personal computers.
Mini-Centronics 36-pin male connector (top) with Micro ribbon 36-pin male Centronics connector (bottom)
The Apple II Parallel Printer Port connected to the printer via a folded ribbon cable; one end connected to the connector at the top of the card, and the other end had a 36-pin Centronics connector.
Serial port
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A serial port is a serial communication interface through which information transfers in or out sequentially one bit at a time. This is in contrast to a parallel port, which communicates multiple bits
Parallel port
…sent one at a time. To do this, parallel ports require multiple data lines in their cables and port connectors and tend to be larger than contemporary serial ports, which only require one data line per direction. There are many types of parallel ports, but the term has become most closely associated with the printer…
A male DE-9 connector on an IBM PC compatible computer (with serial port symbol) used for an RS-232 serial port
A female DE-9 connector on an RS-232 cable.
An IBM PC serial card with a 25-pin connector (obsolete 8-bit ISA card)
A PCI Express ×1 card with one serial port