An NIC (network interface card) is an expansion card that provides connectivity between a PC and a network such as a LAN.
Network Interface Cards are also referred to as ethernet adapters, network adapters, LAN cards, LAN adapters, or NICs (Network Interface Controllers).
Internal network interface cards (NICs) can be either built-in to the system mainboard, as is the case with laptops/notebooks and most modern mainboards, or plugged into an expansion slot inside the device. Modern NIC cards, like that shown on the left, use the PCI bus to interconnect with the system and are very easy to install.
They provide the connectivity for not just ethernet networks, but also Wi-Fi and token-ring networks. NICs can also be used to connect two PCs in a peer-to-peer configuration through the use of a patch cable, which is useful for fast data transfer between the two machines.
One specification is the transfer rate, which is specified in Mbps (Megabits per second), or Gbps (Gigabits per second).
Most modern network interface cards support up to 100Mbps, while the more expensive Gigabit ethernet cards support up to 1000Mbps (1 Gbps).