Two or more local area networks (LANs) connected together, typically over telephone lines or satellite links. In an university, for example, each department usually has its own LAN. These LANs are connected together throughout the university to form a WAN for the entire campus. The transmission medium connecting the LANs together is called a “backbone”, and the information traffic among the LANs is handled by a special computer called a “router”. WANs can, of course, also be connected together, also with the aid of a router.