The Internet is the largest network of personal and enterprise computers in the world. A computer network consists of a number of computers that communicate with each other. In a way, a computer network is similar to a TV network that connects broadcasters to TVs at home. The difference between a computer network and a broadcast network such as a TV network is that a TV network sends the same signal to TVs at the same time while computers on a computer network can exchange messages directly with each other because computer networks are two-way networks.
In reality, the Internet is not one network. It is a network that consists of other computer networks. In some of these networks, computers interact with each other directly. Examples of such networks are corporate networks in which employees communicate with each other. In other networks, there is one main hub and computers mostly interact with the hub. An example of such a network would be an airline information and reservation network. While all computers on such a network are connected to the Internet, they get information about reservation and flight statuses from one central computer.