Today might be the World Wide Web's 25th birthday, but it can't be carbon dated and doesn't have a birth certificate, so it really depends on who you ask.

If you're going by the date when the World Wide Web became publicly accessible, today has a strong claim to the anniversary. The very first Web pages, hosted by CERN, went live in August 1991. After a few weeks of playing around with them internally, the Swiss research institution appears to have flipped the switch on Aug. 23, allowing outside users access to the pages.

Today thus became known as Internaut day, a portmanteau of Internet and astronaut, evoking the pioneering spirit of the first navigators of the Web. But even CERN itself, which has invested resources in restoring the first webpage, doesn't play up Internaut day.

The organization instead refers to the year 2014 as the 25th anniversary of the World Wide Web. That's because CERN researcher Tim Berners-Lee first posted the summary of his World Wide Web project to the alt.hypertext listserv in August 1991. And Berners-Lee had been working on the project well before that: he submitted a proposal for a "distributed information system" in 1989, and engineered the first Web client-server communication over the Internet in December 1990.

Today, Berners-Lee threw cold water on the notion that today is the Web's anniversary.

Who on earth made up August 23? #getitright https://t.co/k76dhmjlNF — Tim Berners-Lee (@timberners_lee) August 23, 2016

The World Wide Web Consortium (W3C) agrees with the 2014 date, and launched a website to celebrate the occasion. In a 2014 interview with Yahoo News, Berners-Lee said many people were skeptical of the idea of connected computers, and didn't see the advantage of sharing data with the world.

There were attempts to make the Web completely private, too. W3C notes that in early 1993, the University of Minnesota announced that it would begin to charge licensing fees for its version of the Web, called Gopher. Many users switched to the World Wide Web, and in April 1993, CERN placed its WWW software into the public domain.

The rest—from AOL to cat videos to Wikileaks to the cloud—is history. Whichever date you chose for the Web's birthday, one thing is clear: an idea born in a Swiss lab filled with listserv-loving tinkerers would usher in an era of global connectivity unlike anything the world has ever seen.