It seems you can't go anywhere in Net circles these days without hearing about tagging or folksonomy or seeing something tagged with keywords. Now, Stephen Green, a leading search expert at Sun Labs, has come along to ponder the usefulness of tags.

Here's an interesting fact upon which I'll base the rest of my argument: people are horribly inconsistent when assigning keywords to documents. If you give two people the same document and ask them to assign a set of keywords to describe it, then the sets of keywords that they assign will agree only about 20% of the time. This was one of the problems that lead to the development of full text indexing systems. If we couldn't choose a few keywords from a document, we would use every word in the document as a keyword!

But Green is not ready to cast off tags completely. He says tags work better when they're drawn from a fixed vocabulary. And there may be a way to create something like that on the Web. An interesting read to take into the weekend.