Tagging for Aboutness
Dave Weinberger, Me on Tagging on All Things Considered
Here's a near-transcript:
Google is smart, but here's a tough problem for it. Let's say you type in "africa," "agriculture" and "grains" because that's what you're researching. You'll get lots of results, but you may miss pages about "couscous" because Google is searching for the word "grain" and doesn't know that that's what couscous is made of. Google knows the words on the pages, but doesn't know what the pages are about. That's much harder for computers because what something is about really depends on what you're looking for. That same page on couscous that to you is about economics could be about healthy eating to me or about words that repeat syllables to someone else. And that's the problem with all attempts by experts and authorities to come up with neat organizations of knowledge: What something is about depends on whose looking.
For more information on tagging, del.icio.us and folksonomy, search the site.