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 LAN card became ubiquitous in Western society in the early part of the twenty first century, when the cards became affordable due to wireless networks springing up everywhere, from coffee shops to airports.
Most home Internet users use this 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 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.
Networks have a variety of security settings, with some being accessible to all users and other requiring a password to access the router. Even when a network is secured, a LAN card will be able to see it and list it as an available network, but when asked to connect will prompt the user for a password. It is recommended that wireless networks be secured to prevent the exploitation of vulnerabilities, and that users never connect to an unknown network.