We're all used to seeing the various parts of the Internet that come into our homes and offices -- the Web pages, e-mail messages and downloaded files that make the Internet a dynamic and valuable medium. But none of these parts would ever make it to your computer without a piece of the Internet that you've probably never seen. In fact, most people have never stood "face to machine" with the technology most responsible for allowing the Internet to exist at all: the router.

Routers are specialized devices that send your messages and those of every other Internet user speeding to their destinations along thousands of pathways. They  forward data packets from one local area network (LAN) or wide area network (WAN) to another or from a network to another connection, like in our diagram: a ground station.

On 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 points and decides which way to send each information packet based on its current understanding of the state of the points it is connected to. A router is normally situated at any gateway  (where one network meets another). A router is often included as part of a network.

Router may create or maintain a table of the available routes and their conditions and use this information along with distance and cost algorithms to determine the best route for a given packet. Typically, a packet may travel through a number of network points with routers before arriving at its destination. Routers are used to  balance traffic within workgroups and to filter traffic for security purposes and policy management. Routers are also used at the edge of the network to connect remote offices.

for more on this check out How stuff works for:

› Introduction to How Routers Work
› Routers Keep The Messages Moving
› Taking Packets from One Place to Another
› How Routers Know Where to Send Data
› Routers Understand the Protocols
› Tracing a Message
› Backbone of the Internet
› Lots More Information!