LAN is a privately - owned computer networks confined to small geographical area, like a factory or an office widely used to connect office PCs to share resources and information. In a Local area network two or more computers are connected by same physical medium, like a transmission cable. A significant characteristic of Local Area networks is speed. It implies that they deliver data very fast compared to other types of networks with typical data transmission speed are 10-100 Mbps.

A wide variety of LANs have been built and installed however a few types have more recently become dominant. Most widely used LAN system is Ethernet system. Intermediate nodes (which are repeaters, switches and bridges) allow LANs to be connected together to form larger LANs. A LAN can also be connected to another WANs or LAN to and MANs using a "router".

In brief, a LAN is a communications network, which is:

• Local (i.e. one building or group of buildings)
• controlled by one administrative authority
• Generally high speed and is always shared

LAN allows users to share resources on computers within an organization.