WAN is a telecommunication network that covers any large metropolitan, regional or national boundaries. This telecomunication system is used in Governments as well as colleges to relay data between employees, clients, buyers and supplyers from all geographical locations. This online system allows all business and communication to be carried out through its daily functions regardless of location or language.
The Most popular WAN is also called the INTERNET. Although there are plenty of different WAN Networks, the majority of which are corporate or research networks that utilize leased lanes .Most WAN networks often connect many smaller networks, like local area networks LAN or metro area networks MAN.
<-- (Google Image)
Here are some other Network systems that are used throughout the world and Links to inform yourself futher.
Here are some easy diagrams of how WAN is incorporated into an existing network.
This Diagram is also another easy to read system that titles all the important connections through a common system