The Internet is formed by networks throughout the world interconnecting and passing on data to each other. A router is a small device that sits between your modem and computer. Most routers are about the same size and shape as a modem. The purpose of the router is to take the information from the modem and deliver it to your computer.
The role a router plays in networking
A router is a networking device that forwards data packets between computer networks. Routers perform the traffic directing functions on the Internet. Routers make the Internet work by forwarding data using a unified addressing system. They can send information to anywhere in the world as long as that location has an IP address.
Look at the following figure, it directly display the relationship between computers and router.
