The Internet is a network of networks that, together, create one large world-wide network. The University of Delaware's campus network is just one small part of the whole Internet. By virtue of having an account on one of the University's central UNIX systems, a Delaware student has access to not just the campus network, but the entire Internet. The Internet is by far the largest computer network in the world. Many networks such as CompuServe, BITNET, America Online, Delphi, GEnie, and others allow members of those networks to communicate with Internet users. These networks are not generally considered to be part of the Internet since users of those networks may only be able to send and receive Email messages and not necessarily access the full range of Internet tools. However they are seeing the benefit (need perhaps to compete) of increasing their members' connectivity to the Internet and are therefore becoming more integrated with the Internet.
The Internet is truly an organic network: it is always growing, new networks are being added and new computers are being added to existing networks. No one really knows how many people use the Internet--nor how many computers are connected to networks that form the Internet. John Naisbett, in his book Global Paradox, estimates that there were 25 million Internet users in the summer 1993, he estimates this number will grow to 350 million users by 1999, 750 million users by 2000 and 1.5 billion users by 2001. Current growth is being fueled by the popularity of the World Wide Web (WWW). A survey conducted by the Commerce Net/Nielson Internet Demographic Survey (April 1996) (http://www.commerce.net/work/pilot/nielsen_96/exec.html) indicated there were 37 million people over the age of 16 with access to the Internet in the US and Canada alone, in August 1995.
Because so many people share so much information over the Internet, you will often hear it referred to as the main component of the Information Superhighway. Imagine several small cities that have paved roads within their city limits. Each city has its own network of boulevards, avenues, main streets and back alleys, but it is an isolated system. At the edge of the city there is nothing. One day, the cityfolk decide to get together and build highways between their cities. As more cities join the highway system, more commerce can take place between the different cities, stimulating further growth in the cities and the road system itself. The Internet has evolved in a fashion similar to the development of a nation's infrastructure! As more and more people share their knowledge over the Internet, its value, population, and resources all increase, therefore its usefulness to each user increases. Unlike a country's road system, the Information Superhighway is not limited by place or time. That is, it is just as easy to communicate with a student in Australia as it is to communicate with another student at the University of Delaware. You can send Email to each other, share your ideas in a Usenet news group, find research data, find detailed product information on WWW and even keep up with current events.