According to Webster's Online Dictionary semantic means "the relationships between symbols and what they represent." Tim Berners-Lee, the man who invented the World Wide Web in 1989 at CERN, the European Particle Physics Laboratory in Geneva, has used the term to christen the Internet of the future.

The Semantic Web is a set of technologies he's developing right now as director of the World Wide Web Consortium, in Cambridge, Massachusetts. Born in London in 1955, Berners-Lee was knighted by Queen Elizabeth II in 2004. In this exclusive interview, he explains his vision of the future Semantic Web, which he says will be much more powerful than anything we have seen before.

First of all, shall I call you Sir Timothy, Professor Timothy or Mr. Berners-Lee?

You can call me Tim.

Well, Tim, my first question is the most obvious one: Can you explain in simple terms what the Semantic Web is?

I have often been asked about that. And the simple thing to point out is: in your computer you have your files, your documents that you can read, and there are data files which are used in applications, data files like calendars, bank systems, spreadsheets. These contain data which is used in documents that are out of the Web. They can't be put on the Web.

So, for example, if you are looking at a Web page, you find a talk that you want to take, an event that you want to go to. The event has a place and has a time and it has some people associated with it. But you have to read the Web page and separately open your calendar to put the information on it. And if you want to find the page on the Web you have to type the address again until the page turns back. If you want the corporate details about people, you have to cut and paste the information from a Web page into your address book, because your address book file and your original data files are not integrated together. And they are not integrated with the data on the Web. So the Semantic Web is about data integration.

When you use an application, you should be able to put data there so that you could configure that data. I should be able to inform my computer: "I'm going to that event." And when I say that, the machine will understand the data. The Semantic Web is about putting data files on the Web. It's not just a Web of documents but also of data. The Semantic Web of data would have many applications to connect together. For the first time there is a common data format for all applications, for databases and Web pages.

Did you come up with the term "Semantic Web?" Is this the so-called Web 3.0? What's the difference between the Webs 2.0 and 3.0?

Yes, I did. It was in 1999, in my book "Weaving the Web." Web 2.0 is a name to describe how the files using the Web work. You have user-generated content, and you have people logging on Web sites and tagging things, uploading a photograph, making community sites. So Web 2.0 is about the community-based Web sites. That is not a term that I invented. Tim O'Reilly invented that term in 2003.

About Web 3.0, some people had used that term to mean a coming architecture. Some people use it to think about the regulation of Web technology. But think about the future of Web technology. A well-known problem which is typical to a 2.0 file is that the data which appears is not on the site, it's in the database. It's not on the Web. So people can't reuse that data. You might take a professional Web site with information about some of your colleagues and the people you work with, and another Web site with information about your friends, and other Web sites about different communities. With Web 2.0 you can't see the whole picture; nobody could see the whole picture. So some people said, well, Web 3.0 will happen when your site provides data that you can navigate. For example, if one of several sites which use Web technology finds useful data about my friends on my journal, then I can set up an icon to inform the computer "Get back data out and look at it and add it to the data which I got from other sites and then look at them all together."

So what's the difference between a Web of documents and a Web of data?

There are many differences between documents and data. Take, for example, your bank data. There's two ways you could look at it. If you just look at a plain Web page, then it looks like a sheet of paper. All you could really do is read it. Now if you look at it on a Web 3.0 site, you could maybe use a Java search to change the order of the data, and you could reach much better access to data.

Today, before you prepare to do something like paying your taxes, you need to use software like Quicken or Microsoft Money or your favorite financial program. When you do that, you don't load it as a Web page, you load it as a data file. That's the difference between data and documents. When you look at your bank data for documents, you can just read it. When you look at data, you can find how much tax you owe, you can see how much your bills are, there are all kinds of things you can do with data.

We don't have the ability to do this with data on the Web. If you could do that with data, the characters you gather with bank data would become a standard that would only work with banks. It's a financial standard for bank data. There will be completely separate standards for calendars, for example. What you can't do today is, say, to ask the computer: "When did I write that check? When did I have that meeting?" You can't connect items in different data files, unless you use the Semantic Web. The Semantic Web is much more powerful, because you can connect the people, connect data, which is about the same person, which is about the same place, which is about the same time.