Just about anyone who's used the Internet has encountered the message Error 404 or Page Not Found. That's what you see when a link is broken or dead, when a resource is no longer available. It happens on blogs. It happens on news websites, even on decisions by the U.S. Supreme Court. Jonathan Zittrain is a professor of law and computer science at Harvard and joins us from Cambridge. Professor Zittrain, thanks so much for being with us.

JONATHAN ZITTRAIN: Hello, Scott.

SIMON: This is called link rot?

ZITTRAIN: Yes. Link or reference rot is the phenomenon by which a URL - uniform resource locator - that you might click on or type in doesn't go where it's supposed to go anymore, maybe because the server where it lives has packed up and gone away, maybe because there's filtering of sometime between you and it. Many reasons why what you thought was only a click away turns out to be hard to find.

SIMON: This is one thing to happen if you're trying to follow a story from BuzzFeed. But if you're a law professor or just a citizen reading a Supreme Court decision, they cite something and the link goes nowhere, that's more than irritating, isn't it?

ZITTRAIN: It's extraordinarily bad for the long-term maintenance of the information we need, say, to understand the law. When the Supreme Court justice offers a URL to explain what he or she is thinking, if you can't follow it and can't get there, or even worse, if something different is there, people can be misled.

SIMON: Something to be done about it?

ZITTRAIN: Well, yes. We found that within the field of law for judicial opinions of the Supreme Court, half of the links were dead already in Supreme Court opinions. And for the Harvard Law Review, just over 70 percent of the links there don't work anymore.

So we've put together a consortium of initially law libraries for which we are offering something called Perma.cc, which is an opportunity for an author or editor of a piece of scholarship or a judicial opinion to take that link that he or she is about to put in there and that's destined to rot probably - take it to one of the participating libraries, have a snapshot made of what's there, and then the Network of Libraries will commit to keeping that indefinitely.

SIMON: I apologize for a humble example, but is this essentially cold storage for data?

ZITTRAIN: Well, it's cold storage that can be warmed up pretty rapidly if need be. In this case, we're really just wanting to make sure that stuff that finds its way into scholarship that used to be stored by libraries systematically and that no longer is because it's just stuff that's borne and lives digitally on the web somewhere, can find a home in a way that preserves the distributed, anarchic web.

SIMON: And does this marvelous new technology come to us for free?

ZITTRAIN: Yes. The idea is this is part of the job...

SIMON: I was being arch when I said that.

ZITTRAIN: (Laughter) The job of universities, of academia and libraries is to be able to serve the basic function of preserving humanity's knowledge. Of course, we don't want to lose money doing it. But we want to make sure that the basic functions of getting the information in and getting it out aren't something that is going to be subject to the whims of a business model or a transfer of ownership of a company. And I should say this is one of several approaches to try to deal with this problem.

SIMON: Jonathan Zittrain, cofounder and director of the Berkman Center for Internet and Society at Harvard. Thanks very much for being with us.

ZITTRAIN: Thank you, Scott.