   a network interface controller (nic, also known as a network interface card, network adapter, lan adapter, and by similar terms) is a computer hardware component that connects a computer to a computer network. early network interface controllers were commonly implemented on expansion cards that plugged into a computer bus; the low cost and ubiquity of the ethernet standard means that most newer computers have a network interface built into the motherboard. == purpose == the network controller implements the electronic circuitry required to communicate using a specific physical layer and data link layer standard such as ethernet, wi-fi or token ring. this provides a base for a full network protocol stack, allowing communication among small groups of computers on the same lan and large-scale network communications through routable protocols, such as ip.  although other network technologies exist (e.g. token ring), ethernet has achieved near-ubiquity since the mid-1990s. every network controller for an ieee 802 network such as ethernet, wi-fi, or token ring, and every fddi network controller, has a unique 48-bit serial number called a mac address, which is stored in read-only memory. every computer on an ethernet network must have at least
Ethernet Networking_hardware