WAN - Wide Area Network
A wide area network is a kind of network that spans over a very large geographical area specifically within a country or the entire globe. This kind of network could be established with the help of a public network, leased lines or satellites. "Internet" is the largest wide area network in existence.
Typically, a WAN is an inter-network of two or more LANs and MANs that are connected together for a specific purpose. This ensures that the computers on one network may securely communicate with the systems located remotely at a far distant location.
This kind of arrangement is best suited to organizations whose branch offices are located at distant geographical locations. It is a matter of necessity for them to connect these locations and make the communication as easy as possible.