"Today, in its (the World Wide Web) clumsy, larval, curiously innocent way, it offers us the opportunity to waste time, to wander aimlessly, to daydream about the countless other lives, the other people, on the far sides of however many monitors in that postgeographical meta-country we increasingly call home. It will probably evolve into something considerably less random, and less fun -- we seem to have a knack for that -- but in the meantime, in its gloriously unsorted Global Ham Television Postcard Universes phase, surfing the Web is a procrastinator's dream. And people who see you doing it might even imagine you're working."
-- William Gibson, "The Net Is a Waste of Time, And that's exactly what's right about it"
The Internet is a world-wide network of interconnected computers. Internet is the present form of cyberspace, or the Matrix.
This is from book Escape Velocity - Cyberculture at the End of the Century by Mark Dery. Although little oldish, it describes well what's happened and tells briefly the history of the Net:
The Internet was born of ARPANet, a decentralized computer network developed at the University of California at Los Angeles in 1969 by the Department of Defence's Advanced Research Projects Agency (ARPA) to ensure military communications in the event of a nuclear attack. By using a technique called packet-switching to disassemble data into addressed parcels, blip them over high-speed lines, and reassemble them just before they reach their destination, ARPANet rendered itself invulnerable to conventional attack; if a portition of the network went down, traffic would automatically be rerouted. In 1983, ARPANet was divided into military and civilian networks (Milnet and Arpa Internet), respectively); shortly thereafter, the U.S. National Science Foundation (NSF) took charge of the administration and maintenance of the lines and equipment that made up the Arpa Internet "backbone". Whereas the Defense Department restricted system access to institutions receiving Pentagon or NSF funding, the NFS made the network available to all faculty and students at member institutions. As universities, R and D companies, and government agencies connected their computers to the NFS's system, what had once been the Arpa Internet mutated into an anarchic global network of networks known, increasingly, as the Internet (from "internetworking").
By 1990, ARPANet had ceased to exist as a discrete entity; the kudzulike growth of the Internet, or Net, as netsurfers have come to call it, had engulfed it. The global metanetwork of today's Net embraces some ten thousand networks, among them nationwide commercial services such as CompuServe, Prodigy, GEnie, and America Online; the private, academic, and goverment institutions interwoven by NSFNET (the NFS's network); and esoteric regional BBSs (bulletin board systems) such as the Sausalito, California-based WELL (Whole Earth 'Lectronic Link) and New York's ECHO. Ming-bogglingly, the Internet is itself part of a still larger complex of interconnected networks commonly called the Matrix, which also includes UseNet (a buzzing hive of discussion groups called "newsgroups"), FidoNet (a constellation of more than twenty thousand BBSs, scattered over six continents), and BITNET (Because It's Time Network, an academic system), among others.
As this is written, an estimated thirty million Internet users in more than 137 countries traverse the electronic geography of what the science fiction novelist William Gibson has called "cyberspace" - an imaginary space that exists entirely inside a computer - and their ranks are growing by as many as a million a month. Based on the rate at which computer networks are building on-ramps onto the Internet, a 1993 estimate put its growth rate at a staggering 25 percent every three months - a delirious pace that shows no sign of abating.
The ephemeralization of labor and the evanescence of the commodity, in cyberculture, is paralleled by the disembodiment of the human. In growing numbers, we are spending ever greater amounts of our lives in cyberspace; like the sagely cyborg in Bruce Sterling's SF novel Schismatrix, we are convinced that "there's a whole world behind this screen". The electronically disembodied are zapping e-mail around the world, typing messages back and forth in real-time "chat", and flocking to BBS discussion topics and UseNet newsgroups. They're lurking and flaming and ROTFLOL (Rolling on the Floor Laughing Out Loud). They're swapping pornographic .GIFs (digitized photos) and swinging in anonymous "text sex" trysts. They're mousing around the Net's latest additions, the World Wide Web, a hyper-text based system that enables users around the globe to point and click from one multimedia site to another, bouncing from digitized video clips to snippets of sound to screenfuls of text without end.
Overwhelmingly, they're convinced that there is a "there" there, after all.