A network interface card is used to connect a computer to an Ethernet network. The card (shown in the figure below) provides an interface to the media. This may be either using an external transceiver (as shown) or through an internal integrated transceiver mounted on the network interface card PCB. The card usually also contains the protocol control firmware and Ethernet Controller needed to support the Medium Access Control (MAC) data link protocol used by Ethernet.
There is also a page showing examples of various types of networking equipment, include NICs for Ethernet.
Each network interface card is assigned an Ethernet source address by the manufacturer of the network interface card (this is normally stored in a PROM on the network interface card). The addresses are globally unique, and are assigned in blocks of 16 (or 8) million address to the Ethernet interface manufacturers, according to a flat addressing structure. This ensures that no two Ethernet network interface will ever have the same source address.
List of Source Addresses
Transceivers and AUI Drop Cables
VLAN and Priority Tags