Router

A router is a device that forwards data packets between computer networks, creating an overlay internetwork. A router is connected to two or more data lines from different networks. When a data packet comes in one of the lines, the router reads the address information in the packet to determine its ultimate destination. Then, using information in its routing table or routing policy, it directs the packet to the next network on its journey. Routers perform the "traffic directing" functions on the Internet. A data packet is typically forwarded from one router to another through the networks that constitute the internetwork until it reaches its destination node.[1]

The most familiar type of routers are home and small office routers that simply pass data, such as web pages, email, IM, and videos between the home computers and the Internet. An example of a router would be the owner's cable or DSL modem, which connects to the Internet through an ISP. More sophisticated routers, such as enterprise routers, connect large business or ISP networks up to the powerful core routers that forward data at high speed along the optical fiber lines of the Internet backbone. Though routers are typically dedicated hardware devices, use of software-based routers has grown increasingly common.

The difference between a router and a switch are the followign.

A router is a more sophisticated device than a switch. Traditional routers are designed to join multiple area networks (LANs and WANs). Routers serve as intermediate destinations for network traffic. They receive TCP/IP packets, look inside each packet to identify the source and target IP addresses, then forward these packets as needed to ensure the datareaches its final destination.

A network switch is a small hardware device that joins multiple computers together within one local area network (LAN). Switches are incapable of joining multiple networks or sharing an Internet connection. A home network with a switch must designate one computer as the gateway to the Internet, and that device must possess two network adapters for sharing, one for the home LAN and one for the Internet WAN. With a router, all home computers connect to the router equally, and it performs the equivalent gateway functions.