On the basis of geographical location:

A.   LAN(Local Area Networks): A Local Area Network (LAN) is a computer network covering a small local area, like a home, office, or small group of buildings

such as a home, office, or college. Current LANs are most likely to be based on switched Ethernet or Wi-Fi technology running at 10, 100 or 1,000 Mbit/s

B.   MAN(Metropolitan Area Networks) : MANs are large computer networks usually spanning a campus or a city. They typically use wireless infrastructure or optical fiber connections to link their sites. For instance a university or college may have a MAN that joins together many of their local area networks (LANs) situated around site of a fraction of a square kilometer. Specifically, this type of MAN is known as a campus area network.

C.   WAN (Wide Area Network): A wide area network or WAN is a computer network covering a wide geographical area, involving a vast array of computers. WANs are

used to connect local area networks (LANs) together, so that users and computers in one location can communicate with users and computers in other locations. Many WANs are built for one particular organization and are private. Others, built by Internet service providers(ISP), provide connections from an organization's LAN to the Internet.