A router is a network device whose task it is to route and/or forward network information. A router has two or more network interfaces, which are to different physical types of or different network standards.
A router distributes Digital computer information that is contained within a data packet. Each data packet contains address information that a router can use to determine if the source and destination are on the same network, or if the data packet must be transferred from one network type to another. This transfer to another type of network is achieved by encapsulating the data with Network specific Protocol header information. When multiple routers are used in a large collection of interconnected networks, the routers exchange information about target system addresses, so that each router can build up a table showing the preferred paths between any two systems on the interconnected networks.