A wide variety of systems of interconnected components are called networks. Specific examples include:

• television networks
• transport networks,
  • roads,
  • railroads,
  • shipping routes and
  • airlines,
  • pipelines (gas, petroleum, water, sewage),
• electric circuits - a network of electrical components.
• digital network - a coupled network of digital (binary) components, for combinational or sequential logic (state machine) implementation
• electricity networks (electric power - generation, transmission and distribution).
• social networks and business networks and entrepreneurial networks, studied in sociology and economics
  • when people meet with each other either for socializing or for assistance, the practice is sometimes referred to as networking. Informal meetings of people are sometimes referred to as the Old Boy Network.
  • sexual networks
  • criminal networks
• computer networks, which transfer information between computers. (Specific configurations include star networks and grid networks.) The Internet is a large-scale computer network. Also, a website and the whole World Wide Web are networks of webpages, a link web. Note: A distinction is made between wide area networks, (WANs) and local area networks (LANs)
• telecommunications networks
  • public switched telephone networks, which route audio signals from one telephone to another
  • radio networks, which create and distribute radio programming
  • television networks, which create and distribute television programming
  • financial networks, for applications such as funds transfer and credit card authorization.
• network externality in economics
• neural network

In mathematics, a network is usually called a graph. To put it another way, network theory is the applied mathematics counterpart of graph theory. General-purpose mathematical models of network structures and associated algorithms have been developed in graph theory. Computer network routing is a direct application of graph theory to the real world.

Networks can be characterized in a number of different ways. For example, many networks are observed to be scale-free networks, in which a few network nodes act as "very connected" hubs.

Further reading

By network scientists:

1. Linked: The New Science of Networks, Albert-Laszlo Barabasi, Perseus Publishing, 2002. Hardcover Textbook. ISBN 0738206679.
2. Nexus: Small Worlds and the Groundbreaking Science of Networks, Mark Buchanan, W. W. Norton, 2002, hardcover, 256 pages, ISBN 0393041530
3. Six Degrees: The Science of a Connected Age, Duncan J. Watts, W. W. Norton, February, 2003, Hardcover: 448 pages. ISBN 0393041425

Consumer studies using network theory:

1. Tipping Point: How Little things Can Make a Big Difference, Malcolm Gladwell, Little, Brown, 2002, trade paperback, 304 pages, ISBN 0316346624
2. Influentials: One American in Ten Tells the Other Nine How to Vote, Where to Eat, and What to Buy, Edward B. Keller, Jonathan L. Berry, Douglas B. Reeves, Free Press, 2003, paperback, ISBN 0743227301
3. Branded: The Buying and Selling of Teenagers, Alissa Quart, Perseus, 2002, hardcover, 256 pages, ISBN 0738206644

(bibliography derived from New York Times article, January 25, 2003 "Connect, They Say, Only Connect" (http://www.nytimes.com/2003/01/25/arts/25WATT.html))

Network is also the title of an Academy Award-winning film.