Local Area Network (LAN)

A local area network (LAN) is a group of computers within a small area, such as a house, office or school, that are connected to each other. Most academic institutions and corporate networks use LANs.

All computers/workstations connected on the LAN can communicate with one another. Each computer has its own resources but is allowed to access other devices on the LAN, provided it has the necessary permissions. This allows users to share data, share expensive resources like printers and scanners, and communicate via email and instant messaging.

The characteristics of a LAN are its arrangement of nodes, the physical media used to connect the nodes, e.g. fiber optic cable, and the communication protocol used to send or receive data. Most current LANs run on Ethernet and use the IEEE 802.3 protocol for communication.

LAN illustration. Image source: Network Elements 

The following characteristics are some advantages of LAN:

• Very high network speeds and data transfer rates
• Protection from the outside world, thus creating a trusted computing environment (Firewalls are usually used to protect LANs and to provide a secure computing environment.)
• No need to lease telecommunication lines, such as those used for telephone, data and Internet services, once the hardware for connecting all the machines has been bought

LANs, however, are restricted to a small geographic range, limited distances, and an upper bound on the number of computers that can be connected on a single LAN.

One LAN can be connected to another LAN over any distance through telephone lines or satellite. Many LANs can also be connected to form a wide area network (WAN), which might, for example, cover an entire town.