I had the good fortune to spend some time with David Weinberger at Syndicate. David is the author of Joho, as well as several other blogs, and is at work on a book about tagging.

I’ll admit that I never gave tagging much thought before speaking to David, but after hearing his perspectives on the potential of this very simple yet powerful technology, I am kind of bowled over.

Think of the Internet as a vast collection of information about very specific topics. For the most part, we have limited information about how to find and identify these topics. Authors tag – or self-classify – their own information because they have to tell people where they think that information should be stored. Publishers and sellers may add to or modify those classifications, but the reality is that they probably don’t change much from what the author intially defined.

In a world bounded by physical limitations, these rigid and very inflexible classifications were necessary. The Dewey Decimal System, for example, dictated that a work of non-fiction had to occupy a single physical space on a shelf, even if that book covered a broad variety of topics. You had to do that in a physical world. But in a virtual world, there’s no need for that kind of rigidity. A book or an article about the Civil War, for example, may belong in the history, military, sociology, anthropology, government and geography sections of a library. You couldn’t possibly classify it that way with a conventional library system. But you can do that – and much more – with tags.

Tags allow authors to self-classify their work – whether it be a book or a blog post – in multiple categories. But what’s cool about services like del.icio.us, digg, TagWorld and many others is that they enable the community to also tag content. So not only authors but readers can classify what an article or other work is about. That means that over time, content can be indexed by what the readers think it is and not just by what the author believes it is.

Think about this, because it’s very powerful. Tags will eventually enable us to subscribe to people, not just to content. I’ll be able to read about what you’re saying about a very specific topic while ignoring what you say about everything else. No offense, but that’s how I’d rather consume information.

Tagging can be applied to anything because anyone can tag any content. So the New York Times can put out an article on Iraq, for example, but if readers decide it’s really an article about Bush’s political agenda, they’ll tag it that way and the classification of that article will change. Over the long term, tagging takes classification out of the hands of the authors and puts it in the hands of the readers. There are plenty of pros and cons to that. I’m not sure I entirely like it, but I’m intrigued by its potential.

David Weinberger has a book coming out on this topic next spring. I’m know it’s going to be on my reading list.