Ethernet is a family of computer networking technologies for local area networks (LANs) and metropolitan area networks (MANs). It is the most popular LAN technology in the world. It is an easy, relatively inexpensive way to provide high-performance networking to all different types of computer equipment.

Ethernet was invented at Xerox PARC and developed jointly by Digital Equipment Corporation, Intel and Xerox. Ethernet has largely replaced competing wired LAN technologies such as token ring, FDDI, and ARCNET.

The Ethernet standards comprise several wiring and signaling variants of the OSI physical layer in use with Ethernet. Over time Ethernet data transfer rates have been increased from the original three megabits per second (Mbit/s) to the latest 100 gigabits per second (Gbit/s)

Systems communicating over Ethernet divide a stream of data into shorter pieces called frames. Each frame contains source and destination addresses and error-checking data so that damaged data can be detected and re-transmitted. As per the OSI model, Ethernet provides services up to and including the data link layer.

The CSMA/CD approach is used by any form of Ethernet operating in half-duplex mode-that is, the mode in which transmit (Tx) and receive (Rx) signals can be sent on the same wire or data path. In full-duplex mode, transmit and receive signals are separated onto dedicated, one-way channels. This eliminates the need for CSMA/CD, as all the transmissions on a single data path will be coming from a single device. Half-duplex mode is seldom used in versions of Ethernet running on fiber, and is not supported at all in the 10 Gbps standards.