WAN, in contrast to a LAN, refers to a wide area network. The name is exactly what it sounds like: a network that covers an area wider than a LAN. Beyond that, the definition is less clear. Distances can range from a network connecting multiple buildings on a corporate or college campus to satellite links connecting offices in different countries. The most popular WAN is the one you’re using to read this article: the Internet. It’s actually a collection of other networks, including other LANs and WANs – hence, the name.
WANs can be wired, using fiber-optic cable, for example, or wireless. A wireless WAN might use microwave or infrared (IR) transmission technology, or even satellite. Laying fiber may make sense when connecting a campus but becomes more expensive when connecting greater distances. To save money, an organization may opt for wireless technology or lease lines from a third party.