How do the network programs of today manage to monitor so many connections?

What exactly is meant by the phrase "computer network"? What are some of the numerous parts that make up a network? In a few sentences, please explain the rationale for the establishment of a computer network.

Is it feasible to establish a network of computers? What different parts of the network make up the whole system? Give a brief explanation of the motivations for building a computer network.

Can we set up a network of computers? How many different things make up the network and what are they? Give a quick explanation as to why a computer network has to be built.