One of the most common network components in a business or at home is a router, however there are a lot of misconceptions of what function a router actually performs.
The reason for this confusion is because so many other components have been incorporated into a modern router that its base capabilities have been lost. In essence, a router moves traffic from one network to another.
If you connect all the computers in your business together (typically with a device known as a switch) you form a Local Area Network (LAN), where all machines can now talk to each other and share information. That is really handy up to the point where you want to start sharing information (say emails) with other networks.
It is at this point you connect a router to your network and another network so users on these two disparate networks can now communicate. The router automatically moves traffic between the two networks without the user having to worry about how it happens.
If you now extend these two connected networks by adding more and more networks connected together with routers, you eventually end up with the Internet as we have it. The Internet is simply massive numbers of networks all connected together using routers.
Routers are intelligent in the way that move traffic between networks because they actually communicate with each other, remembering the paths they need to use to send traffic to destinations. This means they work in a dynamic fashion so that if one route to a destination becomes unavailable they adjust to reflect this change.
The router is the cornerstone of our interconnected world but at its core all it does is simply move data between two different networks.