One type of network device we haven't mentioned is a router. This is because a router generally works at the edge of a LAN rather than within it. A router can operate at a level that is independent of specific LAN protocols so it can be used to join an Ethernet LAN with a LAN that uses different protocols. A router holds information about the structure of a network and can make decisions about how data should be routed through it. As well as being used to connect together different types of LAN, a router connects different types of network. For example, a router would be used to connect a LAN to a WAN.