Network interface controller

A network interface controller (NIC) connects a device to a network and handles data-link-layer communication, including framing and access to the network medium.

Ethernet frame: A data unit used to carry information across an Ethernet link, with addressing and error-checking fields. The NIC assembles outgoing Ethernet frames and processes incoming ones.
Data link layer: The network layer that transfers frames between devices on the same link. A NIC primarily performs functions assigned to this layer.
Wireless network interface controller: A network interface controller that connects a device to a wireless local-area network. Wireless NICs replace a wired medium with radio communication.
Modem: A device that modulates and demodulates signals to carry data over a communication channel. A modem adapts data to a transmission system; a NIC provides the device’s network interface.
Media access control address: A link-layer identifier assigned to a network interface, commonly represented as a 48-bit address. The NIC uses this address to identify itself on a local network.
Physical layer: The layer that transmits raw bits as electrical, optical, or radio signals. A NIC’s physical interface converts frame bits into signals on its medium.
Smart network interface card: A network card with processors or accelerators for offloading network and infrastructure tasks. Smart NICs extend the controller’s role beyond basic frame transmission.
Router: A network device that forwards packets between different networks. A router directs traffic between networks, while a NIC connects an individual device.
Direct memory access: A method that lets hardware transfer data to or from memory without continuous CPU involvement. NICs use DMA to transfer packet data between memory and the network interface.
Network interface: A device’s connection point to a network, implemented in hardware or software. A NIC is a hardware implementation of a network interface.

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