network interface controller (NIC)
A network card, Network Interface Controller ( NIC) or Network Interface Card (NIC), is a printed circuit board or chip that connects the network directly to the end device. It can be a plug-in card for a bus system used in the personal computer: for Industry Standard Architecture( ISA), Peripheral Component Interconnect( PCI) or PCI Express, for Versa Module Europe( VME) or microchannel.
The network adapter card forms the physical interface to the communication network and supports access to the physical transmission medium with its access method. NIC cards are equipped with corresponding sockets for connection to the transmission medium. Network cards are supplied via the system bus, into whose slot they are plugged.
Structure of network cards
Network adapter cards are available for all local area networks( LAN): for Ethernet in the different variants, Token Ring, Fibre Channel or WLANs. As for the versions, they support a wide variety of data rates, ranging from 10 Mbit/s to 100 Gbit/s and above for Ethernet. The NIC card itself covers the functions of the link layer and has its own communications controller, a transceiver and a central processing unit, depending on the version.
Network cards are used in personal computers, workstations, routers or other end devices and network components where they establish the connection to the wired networks, the optical transmission media or by means of Wireless Network Interface Controller(WNIC) to the radio-based WLANs. Since the turn of the century, chips installed directly on the motherboard have also been used instead of network cards. This means that dedicated NIC cards are no longer required.
When a network card is installed in a computer, the corresponding driver is also downloaded. In addition to physical adaptation in the physical layer, most network adapters or NIC chips handle additional communication functions such as transmission security, flow control, compression, I/O interrupts, partitioning, and switched link control.