Router in Networking

A router is a device used in computer networks to connect networks that are dissimilar and that work on different protocols. For example, you are likely to find a router connecting a LAN and a WAN; for instance your private local area network to the Internet. You often get routers from Internet service providers, since these allow you to connect your computer or home network to the telephone line.

This is the definition of routers that most people know.

On a more technical note, a router has a very important role in the mechanism of the Internet and in IP networks in general. It  has a central part in IP networks. 

Each router on a network forwards data packets travelling on that network towards their destinations, based on their IP addresses.

How Router Work

Each router keeps information about its neighbors (other routers in the same or other networks). This information includes the IP address and the cost, which is in terms of time, delay and other network considerations.

This information is kept in a routing table, found in all routers.

When a packet of data arrives at a router, its header information is analyzed by the router. Based on the destination and source IP addresses of the packet, the router decides which neighbor it will forward it to. It chooses the route with the least cost, and forwards the packet to the first router on that route.