Editor's Note (3/12/2019): This article was originally published on March 12, 2009. It is being re-posted on the 30th anniversary of the World Wide Web.

Twenty years ago this month, a software consultant named Tim Berners-Lee at the European Organization for Nuclear Research (better known as CERN) hatched a plan for an open computer network to keep track of research at the particle physics laboratory in the suburbs of Geneva, Switzerland. Berners-Lee's modestly titled "Information Management: A Proposal," which he submitted to get a CERN grant, would become the blueprint for the World Wide Web.

The Web was not an overnight success. In fact, it took nearly two years before Berners-Lee—with help from CERN computer scientist Robert Cailliau and others—on Christmas Day 1990 set up the first successful communication between a Web browser and server via the Internet. This demonstration was followed by several more years of tireless lobbying by Berners-Lee, now 53, to convince professors, students, programmers and Internet enthusiasts to create more Web browsers and servers that would soon forever change the world of human communication.

On Friday March 13, Berners-Lee, Cailliau and other Web pioneers will gather at CERN to celebrate the 20th anniversary of that original proposal. To get the inside story on how the Web came to be, not to mention the man behind the idea, SciAm.com spoke with Scientific American editor Mark Fischetti, who in 1999 collaborated with Berners-Lee to write Weaving the Web: The Past, Present and Future of the World Wide Web by its Inventor, a seminal work that analyzed and commemorated Berners-Lee's achievement a decade after the Web's birth.

[An edited transcript of the interview follows.]

Why was the Web invented at CERN?
Tim Berners-Lee was a software consultant at CERN in the 1980s when he began writing Tangle, an application to help him keep track of CERN's many scientists, projects and incompatible computers. Thousands of researchers would travel to CERN, do their experiments using their own computers (which they brought with them), and then go home to crunch the data. It was a major pain at CERN to accommodate the many incompatible computers, which also had to work with the CERN mainframe that actually ran the mammoth particle accelerators. Tim was responsible for helping everything and everyone work together. He thought it would be a whole lot simpler if the computers could swap their information directly, even though, at that time, computers didn't communicate with one another.

March 2009 marks 20 years since Tim Berners-Lee first proposed a project that would become the World Wide Web. What inspired the larger vision?
He made the proposal to CERN management in March 1989 for funding and an official okay to use some of his time to work on this project. But in thinking about solving the incompatibility problem, he realized that it would be even more cool if the scientists, after they went back to their labs, could still share their data. They might even be able to run some of their experiments at CERN over a network from wherever they were located, if the distant CERN computers could talk over the Internet. The Internet itself is just a set of wires and a protocol for sending information over those wires. The Web would be an application that ran on the Internet. It just so happens that the Web turned out to be the killer app of all time. (Other Internet applications already existed, including File Transfer Protocol, or FTP, and e-mail.)

What were the key innovations that formed the Web? Who created them?
The three main innovations are HTTP (hypertext transfer protocol); URLs (universal resource locators, which Tim originally referred to as URIs, for universal resource indicators); and HTML (hypertext markup language). HTTP allows you to click on a link and be brought to that document or Web page. URLs serve as an address for finding that document or page. And HTML gives you the ability to put links in documents and pages so they connect. Tim created all three of these pieces of software code from October to December of 1990.

What's the best analogy for explaining how the Web works?
Tim likens it to a market economy: anyone can trade with anyone else without having to go to a physical market square to do it. The traders just need to know the rules. The hardest thing for people to grasp about the Web is that it has no center; any computer (or node, in mathematical terms) can link to any other computer directly, without having to go through a central connection point. They just need to know the rules for communicating.

Berners-Lee accessed the first Web page, on the first Web server, using the first Web browser on Christmas Day 1990. Why did it take until 1993 before the public became aware of the creation?
Once Tim and Robert Cailliau established that the Web worked, they wanted to spread the word. After getting CERN to buy in, Tim spent 1991 flying around the world meeting with people who were interested in hypertext and the Internet and linking to create Web browsers to access what was a growing repository of information on Tim's CERN computer. He also encouraged enthusiasts to start their own servers. From there, listservs helped spread the word; so did university computer science programs, which saw the coding of browsers and servers as a great way to get students to experiment. (One of the best known of these projects was headed by the University of Illinois's Marc Andreessen, who would later transform his creation into the Netscape Web browser.) Tim began to get concerned, though, about universities and companies like Microsoft creating their own networks that might compete with the Web, or charging for content, which would violate his core principle: that everyone should be able to communicate freely with everyone else. To stop this from happening, he got management at CERN to release all of his source code under a general license so that any programmer anywhere could use it for free. He thought that if the whole world was building the Web together, no one company could take control of it.

What caused the Web to finally take off?
Tim designed the Web to be a social medium, first, rather than a technical one—a system that would connect people through their computers, and the grassroots building [of the Web] took off because of that. However, the general public didn't really enter that picture until the mid-1990s, when companies like Netscape and AOL [America Online] commercialized browsers. These companies would snail mail free CDs with their browser software so people would get on the Web, hoping that once they got there, they would discover services the companies offered for a fee, such as e-mail.

Why did Berners-Lee abruptly leave CERN to begin the World Wide Web Consortium at the Massachusetts Institute of Technology in 1994, just as the Web began to rapidly expand?
At that point, the Web was clearly becoming a juggernaut, and commercial forces did indeed threaten those core principles. CERN was not in the business of overseeing Internet systems or applications—it existed to do high-energy physics experiments. Tim couldn't be the caretaker and stay there, so he moved on to M.I.T.'s Laboratory for Computer Science,  which became the host for a new World Wide Web Consortium, where Tim has been ever since.

What has most surprised him about the Web's evolution?
What surprised Tim most is that for years people were so much more interested in simply browsing for and reading content rather than in creating it. His very first browser—WorldWideWeb—was actually both a browser and an editor. It let you write your own pages, post them online, and edit pages posted by others. But the commercial browsers didn't offer editing capabilities. This frustrated him for a number of years. The whole point of the Web, to him, was not to just see information but to publish it, too. This didn't really happen until blogs emerged, followed by sites like Facebook, where people can easily post content.

What does the future hold for the Web, given that the openness that Berners-Lee built into it is continually exploited by miscreants?
It's hard to implement controls on the Web—because it was created in the ethos of the Internet—in that it's totally open. But for Tim, confronting issues like privacy and protection of intellectual property is not a matter of a technical fix. First, you need a social fix. If the Web is open to good people, it's open to bad people, too. The way you deal with security and other problems on the Web is the same way you deal with it in society: You need laws and social conventions that guide people's behavior. Once those are developed, then the technical ways to implement them can be created.