hypertext meets the network
The internet and the World Wide Web are not the same thing, even though people say "the web" when they mean "the internet" constantly. The internet is the plumbing; the Web is one thing that runs on it. In 1989, a researcher at CERN named Tim Berners-Lee proposed a way to link documents across computers using hypertext. By Christmas 1990 he'd built the first web browser, the first web server, and the first website — and on 6 August 1991 he made it public.
The recipe was three ideas that turned out to be enormously portable: HTML to write pages, HTTP to fetch them, and the URL to address them. Simple enough that anyone with a text editor could make a page, which is exactly what happened next.
The turning point for ordinary people was the browser. NCSA Mosaic launched in 1993 and put images inline with text for the first time, which made the web feel like a magazine instead of a terminal. Its creators went on to found Netscape, whose Navigator browser (1994) is the reason half the internet still argues about browser compatibility today. By the end of 1994 there were roughly 10,000 websites online. By the end of the decade there would be millions.