Actually, I think Dr. Berner Lee helped the internet take off a bit in early 90s (maybe even 1990). But Marc Andreesen is one of the most responsible "people" to help the internet take off. He developed the first browser (mosaic)[Netscape guy] which makes it much easier for us all to browse the net.
Of course the HTML above is also a big answer - the browser basically interprets HTML code and allows us all to view the sites
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