In its broadest definition, a global network is a chain of connections that link people around the world in a flow of communications, services, money, information, and goods. Using this broad definition, we might identify transnational corporations (TNCs) and multinational corporations (MNCs) as global networks, for they span the whole world as they produce and sell their products. Apple, Microsoft, and McDonald's are prime examples of companies that do business throughout the world.
Most definitions of "global network," however, limit the term to its application in communications. In this case, a global network is a communication system that spans the world. Most of us immediately think of the Internet when we hear this definition. The Internet is simply a network of computers linked by cables, satellites, and wireless systems. These computers can access information from around the world and provide instant communication with people in any location where the Internet reaches.
Other examples of global networks (in terms of communications) include mobile wireless networks that provide cellular service for cell phones and other devices; communications satellites like Globalstar; and even international mail services (which do indeed allow communication to spread throughout the world).
Global networks have become so familiar to us these days that we hardly think about them. They are simply part of our lives, whether we're talking about a TNC or the Internet. Yet it is good to occasionally step back and think about how connected our world has become even compared to a couple decades ago. When we purchase a product made in another country, make a call on a cell phone, or look up something on the Internet, we are participating in a global network.