Network interface controller (NIC) LAN Cards and How Does a LAN Card Work ITS TYPES

A network interface card, more commonly referred to as a NIC, is a device that allows computers to be joined together in a LAN, or local area network. Networked computers communicate with each other using a given protocol or agreed-upon language for transmitting data packets between the different machines, known as nodes. The network interface card acts as the liaison for the machine to both send and receive data on the LAN.
The most common language or protocol for LANs is Ethernet, sometimes referred to as IEEE 802.3. A lesser-used protocol is Token Ring. When building a LAN, a network interface card must be installed in each computer on the network and all NICs in the network must be of the same architecture. For example, all must either be Ethernet cards, Token Ring cards, or an alternate technology.
An Ethernet network interface card is installed in an available slot inside the computer. The NIC assigns a unique address called a MAC (media access control) to the machine. The MACs on the network are used to direct traffic between the computers. The back plate of the network interface card features a port that looks similar to a phone jack, but is slightly larger. This port accommodates an Ethernet cable, which resembles a thicker version of a standard telephone line. Ethernet cable must run from each network interface card to a central hub or switch. The hub or switch acts like a relay, passing information between computers using the MAC addresses and allowing resources like printers and scanners to be shared along with data.
A network interface card does not have to be hard wired with physical cable. Wireless Ethernet cards are installed like their wired counterparts, but rather than a port for an Ethernet cable, the card features a small antenna. The card communicates with the central wireless switch or hub via radio waves. Wireless LANs may have some restrictions depending on the material the building is made from. For example, lead in walls can block signals between the network interface card and hub or switch.
When buying components for a LAN, make sure the NICs and hub or switch have the same capabilities. The entire network must be either wired or wireless, so a wireless network interface card cannot talk to a wired switch or hub. In addition, newer versions of hardware will likely support more features and/or greater speeds than older versions. Make sure your central switch or hub can utilize the highest capabilities of the network interface card under consideration.  

Purpose

The NIC allows computers to communicate over a computer network. It is both an OSI layer 1 (physical layer) and layer 2 (data link layer) device, as it provides physical access to a networking medium and provides a low-level addressing system through the use of MAC addresses. It allows users to connect to each other either by using cables or wirelessly.
Although other network technologies exist (e.g. token ring), Ethernet has achieved near-ubiquity since the mid-1990s.
Every Ethernet network card has a unique 48-bit serial number called a MAC address, which is stored in ROM carried on the card. Every computer on an Ethernet network must have a card with a unique MAC address. Normally it is safe to assume that no two network cards will share the same address, because card vendors purchase blocks of addresses from the Institute of Electrical and Electronics Engineers (IEEE) and assign a unique address to each card at the time of manufacture.

Madge 4/16Mbps TokenRing ISA NIC

Ethernet 10Base-5/2 ISA NIC Whereas network cards used to be expansion cards that plug into a computer bus, the low cost and ubiquity of the Ethernet standard means that most newer computers have a network interface built into the motherboard. These either have Ethernet capabilities integrated into the motherboard chipset or implemented via a low cost dedicated Ethernet chip, connected through the PCI (or the newer PCI express) bus. A separate network card is not required unless multiple interfaces are needed or some other type of network is used. Newer motherboards may even have dual network interfaces built-in.

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How Does a  LAN Card Work

A Local Area Network (LAN) card is used to provide wireless Internet access to computer users in home or roaming networks. It works by exchanging signals with a router, which transmits the signals over a physically wired line. The card became ubiquitous in Western society in the early part of the twenty first century, when the LANcards became affordable due to wireless networks springing up everywhere, from coffee shops to airports...Most home Internet users use a LAN card for wireless Internet access so that multiple residents can be on the Internet at the same time. The router is placed in a central location in the home to provide even signal across the household. Wireless networks are also widespread on college campuses, so that students with laptops can use the Internet wherever they may be. The value of wireless to attract customers has been recognized by restaurants and other such businesses, who usually provide network access in exchange for a small fee or purchase of their product.

A LAN card communicates with the router using radio waves and an antenna. The computer converts data into binary form and sends it to the LAN card, which in turn broadcasts the signal to be picked up by the router. The router sends the information on in the form of packets of information, and bundles information for return to the computer via the LAN card in the same way. Usually wireless networks transmit at a relatively high frequency, ranging between 2.4 and 5Ghz, designed to accommodate the more rapid transfer of large amounts of data. When purchasing a router or LAN card, the packaging will indicate the frequency of the signal it uses.

Multiple users can maintain a connection to the router on different bands, to avoid interference, and are assigned unique identities by the router in the form of an IP address. Each user attempting to access the network will need a LAN card, which is either available built into the computer or as an external attachment which can be connected through a Universal Serial Bus port or PC card slot in a laptop.

Local area network A local area network (LAN) is a network that connects computers and devices in a limited geographical area such as home, school, computer laboratory, office building, or closely positioned group of buildings. Each computer or device on the network is a node. Current wired LANs are most likely to be based on Ethernet technology, although new standards like ITU-T G.hn also provide a way to create a wired LAN using existing home wires (coaxial cables, phone lines and power lines). Typical library network, in a branching tree topology and controlled access to resources All interconnected devices must understand the network layer (layer 3), because they are handling multiple subnets (the different colors). Those inside the library, which have only 10/100 Mbit/s Ethernet connections to the user device and a Gigabit Ethernet connection to the central router, could be called "layer 3 switches" because they only have Ethernet interfaces and must understand IP. It would be more correct to call them access routers, where the router at the top is a distribution router that connects to the Internet and academic networks' customer access routers. The defining characteristics of LANs, in contrast to WANs (Wide Area Networks), include their higher data transfer rates, smaller geographic range, and no need for leased telecommunication lines. Current Ethernet or other IEEE 802.3 LAN technologies operate at speeds up to 10 Gbit/s. This is the data transfer rate. IEEE has projects investigating the standardization of 40 and 100 Gbit/s. ______________________________________________________________________     Another type of LAN card is Ethernet card Ethernet card:  The Ethernet card was created to build a Local Area Network (LAN). Once Ethernet cable is connected to the Ethernet cards of two or more computers over the LAN, one can transfer files and data. This can be carried out for external hardware such as printers and scanners when information from one computer needs to be transferred to another computer.