A router, which is responsible for sending information from one network to another, is an important network device because most companies are connected to the Internet. When a computer on your network wants to send information to a computer on another network, your computer passes the information to your router.
The figure shows three different networks, each connected to the Internet by a separate router. All computers on network A know that any information with an outside-network destination must be passed to the router because the router is the only device with a physical connection to the outside world.