The internet goes back to early 1970s and gradually became available to increasing numbers of people via email, text-based discussion channels (usenet), gopher, and other things. All of those existed when I came here from Sussex University in 1991.
At that time, the World Wide Web, allowing documents to be accessed remotely, without having to be transmitted explicitly (e.g. by the author) to a set of named recipients, was just over the horizon, but within a few years it had begun to overtake everything else. It used the infrastructure provided by internet, which was initially available only to a small international collection of research centres, government departments, and some university departments, e.g. computer science, physics, electrical engineering, and possibly others.
I probably used the internet before anyone else on this campus and most people
in the world, in 1974, sitting in Sussex University at a paper teletype (10
characters per second printing speed), typing (via multiple cable and wireless
(satellite) connections) into a machine belonging to the new Xerox Palo Alto
Research Centre (PARC). (This was thanks to Danny Bobrow, who arranged for me to
have access to the Xerox machine, and Max Clowes who allowed me to use equipment
provided by the UK Science Research Council for his AI research.)
I am now able to work at home, logged in to my linux PC on my desk in CS, using it as if it were on my desk at home, thanks to the internet. Thanks to the facilities provided by our departmental computer officers, I can also install documents, images, videos, program files, onto our web server, so that they can be accessed by anyone on the planet, e.g. this paper on teaching intelligent design: http://www.cs.bham.ac.uk/research/projects/cogaff/misc/teaching-intelligent-design.html (also PDF)
Unfortunately, the internet is now widely abused. For the time being the good outweighs the bad, however.