A network card also called a network interface card (NIC), an ethernet card, a LAN adapter and a network adapter is a computer device that allows computers to communicate over a network.
In older systems NICs were plugged into the computer's motherboard PCI slots and provided a port for connecting to a computer network. This practice has ceased and network adapters are now integrated into motherboards.
There are exceptions to onboard network adapters because in the gaming sector there are some super-fast discrete gaming network adapters.
All network adapters are manufactured with a unique address called Media Access Control (MAC). This assumes that no two cards have the same MAC address.
During the manufacturing process, network card producers purchase blocks of MAC addresses from the Institute of Electrical and Electronics Engineers (IEEE) and assigns this unique address to each card at the time of manufacture.
Connection to your system motherboard is done via the following methods - Integrated, PCI Connector, PCI-E, FireWire and USB. Connections to the network is achieved using the following technologies - Fast Ethernet, Gigabit Ethernet, Optical Fiber and Token Ring.
Network speeds have increased over the years from 10 Mbit/s to fast 100 Mbit/s to the extra fast 1,000 Mbit/s (Gigabit).
The card and its device drivers are the only components in the system that recognize the type of network being used. This means the type of network being used is only transparent to the application software using it.
The network card, also called a network interface card (NIC), sends and receives data to and from the system bus in parallel and sends and receives data to and from the network in series.
The card also converts the transmitted data into a signal that is appropriate for the network. Examples of this are:
The fiber optic FDDI card has a laser diode that converts the data to light pulses for transmission.
The twisted-pair ethernet card converts the data from the 5-volt signal to the voltage used by the twisted-pair cable.
The component on the card that performs the signal conversion is called the transceiver.
Some ethernet cards have more than one transceiver with different ports to allow for different cabling. Such a card is known as a combo card.
Each card requires an IRQ (Interrupt Request) and an I/O (Input/Output) address.
Most present day cards are Plug and Play. Gone are the days of setting jumpers of dip switches to determine which resources to request.
Finally, when selecting a network card, remember these important factors:
The type of network you are connecting to (Ethernet, Token Ring or FDDI).
The type of cable you are using (shielded twisted-pair, coaxial or fiber optic cable).
The type of I/O (Input/Output) bus you are connecting the card to .... be it PCI (Peripheral Component Interconnect), PCI-E, FireWire or USB.
And for all you extreme online gaming enthusiasts, think about getting a 'killer' network card.