The Internet: the most famous Wide area Network is a packet switched one: the INTERNET network

This is an example of how networks of a different type are attached together to in the way of the internet. We see an ethernet, two token-ring networks and an ATM network. R1, R2, R3, and R4 are the so called "routers" which connect two or more different local area networks together. The router R4 is shown here as the gateway from this cluster of networks to the rest of the internet.