Ethernet is the family of wired networking technologies that came to dominate the local-area network (LAN). It was invented at the Xerox Palo Alto Research Center, where Robert Metcalfe circulated his founding memo in May 1973 and built the first working system with David Boggs to connect PARC’s Alto personal computers. The design was first described in public in the July 1976 Communications of the ACM paper “Ethernet: Distributed Packet Switching for Local Computer Networks,” whose abstract calls Ethernet “a branching broadcast communication system for carrying digital data packets among locally distributed computing stations.”
The original Ethernet used a single shared coaxial cable, the “Ether,” that every station tapped into. There was no central controller; instead stations used a method the inventors called controlled statistical arbitration, later standardized as Carrier Sense Multiple Access with Collision Detection (CSMA/CD). A station listened before transmitting, and if two stations transmitted at once and their signals collided, both detected the collision, stopped, and retried after a randomized backoff. The 1976 paper reported operational experience with roughly 100 nodes spread along a kilometer of coaxial cable running at about 3 megabits per second.
The technology was assigned to Xerox in US Patent 4,063,220, “Multipoint Data Communication System With Collision Detection,” filed in March 1975 and granted in December 1977, naming Metcalfe, Boggs, Charles Thacker, and Butler Lampson as inventors. To turn Ethernet into an open industry standard rather than a single-vendor product, Xerox joined with Digital Equipment Corporation and Intel to publish the “DIX” Ethernet specification at 10 megabits per second around 1980.
The IEEE then standardized the technology through its 802 committee. IEEE 802.3-1985, formally titled “Carrier Sense Multiple Access with Collision Detection (CSMA/CD) Access Method and Physical Layer Specifications,” became the canonical reference, and the standard has since been renamed simply “IEEE Standard for Ethernet.” Over the decades 802.3 absorbed twisted-pair cabling (10BASE-T), fiber, and switched full-duplex operation, growing from 10 megabits per second to speeds measured in hundreds of gigabits per second, while CSMA/CD itself became largely vestigial as shared coaxial buses gave way to point-to-point links and switches.
Ethernet’s combination of simplicity, openness, and steady standardization let it outlast competing LAN schemes such as Token Ring and ARCNET. Its inventor, Robert Metcalfe, received the 2022 ACM A.M. Turing Award “for the invention, standardization, and commercialization of Ethernet,” a citation that captures why Ethernet matters as much as a standards story as a technical one.