Ethernet is the most widely used hardware connection standard for LANs (local area networks). It was first developed by Xerox Corporation in cooperation with DEC and Intel in 1976. It was later refined (known at the time as Ethernet-II and then adopted as an open standard, designated 802.3 by IEEE.

Ethernet uses the CSMA/CD access method to handle collisions when multiple systems try to access the LAN simultaneously.

Ethernet currently provides bandwidths of 10mps (traditional Ethernet), 100mps (fast Ethernet), 1 gig, and 10-gigabit. Older Ethernet usually ran over a coaxial cable that nodes tapped into (bus architecture). Most new Ethernet installations consist of a star topology where each computer connects to a central hub with a single cable. This cabling is sometimes referred to as home runs. In this system Category 5 cabling is used to connect the nodes (computers) to the hub.