What is a network interface card (NIC)? Definition from SearchNetworking

What is a network interface card (NIC)?

A network interface card (NIC) is a hardware component, typically a circuit board or chip, which is installed on a computer so it can connect to a network. Modern NICs provide functionality to computers, such as support for I/O interrupt, direct memory access (DMA) interfaces, data transmission, network traffic engineering and partitioning.

A NIC provides a computer with a dedicated, full-time connection to a network. It implements the physical layer circuitry necessary for communicating with a data link layer standard, such as Ethernet or Wi-Fi. Each card represents a device and can prepare, transmit and control the flow of data on the network.

The NIC uses the OSI model to send signals at the physical layer, transmit data packets at the network layer and operate as an interface at the TCP/IP layer.

The NIC performs different functions for different layers of the OSI model.

The network card operates as a middleman between a computer and a data network. For example, when a user requests a webpage, the computer will pass the request to the network card, which converts it into electrical impulses.

A web server on the internet receives the impulses and responds by sending the webpage back to the network card as electrical signals. The card gets these signals and translates them into the data that the computer displays.

Originally, network controllers were implemented as expansion cards that could be plugged into a computer port, router or USB device. However, more modern controllers are built directly into the computer motherboard chipset. Expansion card NICs can be purchased online or in retail stores if additional independent network connections are needed. When purchasing a NIC, specifications should correspond with the standard of the network.

The term network interface card is often considered interchangeable with the terms network interface controller, network adapter and LAN adapter.