Internet, Networking, & Security Home Networking What are Serial (COM) Ports in Networking? by Bradley Mitchell Writer An MIT graduate who brings years of technical experience to articles on SEO, computers, and wireless networking. our editorial process LinkedIn Bradley Mitchell Updated on November 24, 2018 Tweet Share Email Monty Rakusen / Getty Images Home Networking The Wireless Connection Routers & Firewalls Network Hubs ISP Broadband Ethernet Installing & Upgrading Wi-Fi & Wireless 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. Serial Ports Are Outdated Serial Ports were phased out when USB and wireless connections came into use in the early 2000s. USB was much faster, easier to use, smaller, and less complicated than serial. These days it's hard to find a computer that has the older serial ports, much input (mice or keyboards, for example) or other peripheral devices that require them. Standards For Serial Ports 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. 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 applied to many Macintosh computers. Both of these standards are now obsolete in favor of USB or FireWire standard ports and serial communication. Also Known As: COM port Was this page helpful? Thanks for letting us know! Get the Latest Tech News Delivered Every Day Email Address Sign up There was an error. Please try again. You're in! Thanks for signing up. There was an error. Please try again. Thank you for signing up. Tell us why! Other Not enough details Hard to understand Submit