Wide Area Network
A Wide Area Network (WAN) is a computer network that covers a very large geographical area. A WAN may interconnect multiple Metropolitan Area Networks or Local Area Networks, and provide uplink service to the Internet.
Usually WANs are built by private organizations and can span across countries or even continents, interconnecting networks using numerous solutions. Since the distance covered can be so big, WANs are often built on leased communication lines as laying new lines might be too expensive or even impossible.
WANs can also be built using circuit switching or packet switching to save costs of leasing lines.
In recent years, more and more firms have turned to Virtual Private Networks instead of establishing WANs. These VPNs are built on top of normal Internet protocols and can be accessed by a computer or LAN connected to the Internet, with the right credentials.