A network is any interconnected system. The Internet is a network of computers all talking to one another. A subway is a network of interconnected train lines running underneath the city.
A wise man once said that if the atom was the symbol of the 20th century, the network should be the symbol of the 21st. Increasingly our world relies on networks, the vast interconnected systems of people, electronics, ideas and even resources. To put pressure on any one part of a network is to put pressure on all parts, because, by definition, a network is interconnected. Whether the network is a television network, a cellular network, or a social network — each is a vast system of interconnected parts.