An Ethernet port (also called a jack or socket) is an opening on computer networking equipment into which Ethernet cables are inserted. Their purpose is to connect wired network hardware to an Ethernet LAN, metropolitan area network (MAN), or wide area network (WAN).

Ethernet ports are located on the back of a computer or the back or side of a laptop. A router may have multiple Ethernet ports to accommodate multiple wired devices on a network. The same is true for other networking hardware such as hubs and modems.

An Ethernet port accepts a cable with an RJ-45 connector. The alternative to using such a cable with an Ethernet port is Wi-Fi, which eliminates the need for both the cable and the port.

An Ethernet port is slightly wider than a telephone jack. This shape makes it impossible to fit an Ethernet cable neatly into a telephone jack, which makes it a little easier to plug in cables.