The history of the Internet:
Approximately 20 years ago, the US Department of Defense set up a computer network called the ARPAnet, which was designed to aid military research. In order to minimize the vulnerability of the system, it was designed to be decentralized; that is, a chunk of the network could be missing (bombed in a nuclear attack, perhaps), but the remainder of the network would keep functioning. This assumption that the network itself would be unreliable has turned out to be a good one; if history has taught us anything about computers, it is that they are reliably unreliable.
The next revolution in networking occurred 10 years later, when local area networks (LANs) began to emerge. These networks included bulletin board systems, mainframe-served workstations, and the like. Our Wang system is a good example of this kind of thing. And in fact, dial-in mainframes became so popular as businesses and universities came to realize the potential of the resources they had at their fingertips, that in 1987 a contract to revamp and upgrade the most heavily used supercomputer network in the country (which happened to be the National Science Foundation's five supercomputer centers) was awarded to Merit Network in partnership with IBM and MCI.
The National Science Foundation began a program which would fund university access to its supercomputers only if universities would promise to spread the access around. Now, most universities and many businesses have their own mainframe computers, and the communications which link them tend to be very similar. So while at one time the NSF was the "hub" of the Internet (and in fact still acts as a franchisor of Internet access points), now there are millions of hubs. These hubs are interconnected, so that if you can access one, you can access 'em all.
As of January of 1994, one estimate placed the number of computers linked to the Internet at 2.2 million -- and growing at an exponential rate. This only counts "hub" computers, not the desktop computers which link into them. The following chart will give you some idea of the rate of Internet expansion.
Amazing, isn't it? I read an estimate that there are over 30 million Internet users on these machines, and my opinion is that the estimate is too low.
