Local Area Network (LAN)

Description of LANs

LANs traditionally refer to the physical connections between two or more computers within a given space (typically, a room or a building). Wire cables usually comprise these physical connections between these computers: although coaxial cables were typically used in the past, twisted pair cables and fiber-optic cables are now primarily used in modern LANs. These physical, wired connections allow computers to perform a range of functions that is not possible for one computer to perform alone; typically, these wires connect to a router, modem, or other centralized device. Contemporarily, LANs are increasingly becoming wireless because of the availability of wireless connectivity, such as the service provided by the Wi-Fi Alliance.

Since the inception of LANs, a major functional goal for a LAN is to enable the sharing of resources among computer users within a small geographic area. For example, computers in a LAN can all be connected to the same printer: this allows for cost savings (because not all computers in the LAN need their own printer) and time savings (because a shared printer does not have to be continually connected and disconnected to each computer when a different computer user in a LAN needs to use the printer). One concern of sharing resources like a printer on a LAN is that two or more computer users on a LAN will send a command at the same time. One way that LAN inventors like Harry Pyle have tried to address this problem is through the invention of collision detection, which allows command signals to back off for a few milliseconds before trying to resend.

In addition to making shared resources possible, LANs can provide other opportunities for communication among users. In the early days of LAN, computer makers included software that was already activated for internal communication among users of LAN-connected computers: users could instant-message other users in a LAN. Such software is still provided on personal and business computers, but users typically must pursue additional steps in order to activate this software (sometimes through purchasing additional, complementary software). The growth and popularity of instant messaging and other communication tools on WANs (wide area networks) like the Internet has corresponded with the decline of such tool use on LANs.

LANs are only one type of computer network. WANs span entire cities and countries, and MANs (metropolitan area networks) span entire campuses and sections of cities (like neighborhoods). WANs and MANs can be (but are not always) comprised of an interconnected series of LANs. LANS can share Ethernet or other connections to the Internet and have been viewed as a step toward wide-scale connectivity, even though they usually serve as local connectivity between computer users.

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