You can also say that a router is a specialized computer that can connects two or more than two computers.
Therefore router is called as Internetworking device. Internetworking is a network that connects two or more than two networks. In other word internetworking is a network of network.
With the help of router, internetworking can be done or network of network can be made.
As i told you that router is also a computer but this computer is specially designed for the routing purposes only. We can also use our computer as a router also called as software router. But if we compare software router (our computer) to a hardware router (router), then our computer software router works too slower than hardware router that is specially designed for the routing purpose.
There is a Operating system and a software present in the router, with the help of this router moves the data from one network to another.
For its help, it creates a routing table and that table called as routing table. With the help of routing table router sends the data from one network to another network.
In case, if the destination is unknown to a router it sends the traffic (bound to unknown destination) to another router (using logical addresses) which knows the destination.
A router differs from a bridge in a way that former uses logical addresses and the latter uses physical addresses.
Router can also be used to control the broadcast traffic.
Too many company that made routers such as Cisco, Juniper, 3Com, HP, Nortel etc. There are two many companies that made routers but the above are popular company in making routers.
The main function of router is to connect networks together.
Routers use a more complete packet address to determine which router or workstation should receive each packet next.
Based on a network road map called a routing table, routers can help ensure that packets are travelling the most efficient paths to their destinations.
In case, if a link between the two routers fails, then the sending router can determine an alternate route to keep the traffic moving.
Router works on the Network layer or layer 3 of OSI model.