An Ethernet network is a type of computer networking technology standardization for local area networks (LANs). It was commercially introduced in 1980 and has become the most common wired LAN technology. Ethernet uses a bus topology or star topology, as well as point-to-point links between devices. Ethernet addresses are six octets long. The data link layer standards of IEEE 802 define Ethernet frame formats.
Ethernet operates at the data link layer of the OSI model (Layer 2), where network protocols such as TCP/IP are implemented on top of it. An important characteristic that distinguishes Ethernet from other physical Layer 1 technologies is its use of MAC addresses instead of node IDs to identify hosts on the network segment. This allows each message to be addressed to a specific host rather than broadcasted indiscriminately across all attached nodes, which improves overall efficiency and reduces collision domains. In addition, due to broadcast traffic being limited by design, collisions only occur when two or more hosts attempt to send simultaneously, which further reduces their likelihood compared with technologies using carrier sense multiple access with collision detection (CSMA/CD) schemes like Wi-Fi.
The first version of what became IEEE 802.3 was released in 1980 as “The Ethernet CSMA/CD Access Method and Physical Layer Specifications”. Version 2 was published in 1982 and changed little except for renaming CSMA/CD to Carrier Sense Multiple Access with Collision Detection or Carrier Sense Multiple Access with Collision Avoidance depending on whether early detection collision avoidance circuitry had been added into NICs; this name change reflected operational experience gained since the initial release. After several revisions that incorporated numerous improvements over earlier versions including support for much higher speeds up through one hundred Gbit/s., The Institute of Electrical and Electronics Engineers (IEEE) standardized 802.3bx under IEEE Std 802.