The Router

In packet-switched networks such as the Internet, a router is a device or, in some cases, software in a computer, that determines the next network point to which a packet should be forwarded toward its destination. The router is connected to at least two networks and decides which way to send each information packet based on its current understanding of the state of the networks it is connected to. A router is located at any gateway (where one network meets another), including each point-of-presence on the Internet. A router is often included as part of a network switch.
Routers forward data packets across computer networks. A Router checks the data packet for its destination address and protocol format details. If the router microprocessor finds a match in its address tables, it routes it to that destination address. If the destination address is on a network type that uses a different transmission protocol, the appropriate new protocol data is added to the packet.