Serial Port

In computer networking, a serial port enables external modems to connect to a PC or network router via a serial cable. The term "serial" signifies that data sent in one direction always travels over a single wire within the cable.

The prevailing standard for traditional serial port communications historically has been RS-232. These serial ports and cables are the same used for PC keyboards and other computer peripheral devices (see sidebar). Serial ports and cables for RS-232 PCs generally feature 9-pin DE-9 connectors, although 25-pin DB-25 and other variations exist on specialized hardware. The alternative RS-422 standard applies on many Macintosh computers.