I spend a lot of time reading about various ways to organize and re-find data. The concepts of these techniques range from very high-level concepts that are complicated to use, hard to build and to manage, such as Topic Maps over sightly loosened ways like XFML (eXchangeable Faceted Metadata Language) to anarchic, ad-hoc methods like my Topical and, finally Tags.
The more complicated the technique is, the lesser will it scale and distribute. Trying to build a Topic Map as a collaborative effort sounds like suicide. Tag webs are build everyday, however. del.icio.us and Technorati Tags demonstrate this daily.
Now, why do tags work?
I first had a hard time believing that tags are useful and scale. After all, tags are essentially one-dimensional faceted metadata. When I built Topical, I knew this and invented “n-dimensional tags”, in that you could build a hierarchy of tags. They work wonderfully for me, but I use them alone. They will not scale very good, and I know that. Especially, you need one to maintain the tag hierarchy.
Over the time, however, as usage of del.icio.us raised, and Technorati started to use tags too (and their wonderful idea of combining tags of several sites, such as del.icio.us and furl.net), I really wondered why they work.
The reason tags work is that tags are common-sense. The less complex your hierarchy of categorization (there is none in the case of tags) is, the more likely it is that people will do the Right Thing on their own. As Technorati says (emphasis mine):
Think of a tag as a simple category name. Bloggers categorize their posts, photos, and links with any tag that makes sense.
Also, tag webs can be picked-up easily. You read del.icio.us and you pickup tags. Maybe you stumble on one tag you don’t really know what it has behind, so you click on it and see what it relates too. If you want to tag data on your own now, you learned a new tag you can use where appropriate. And there are lists of often-used tags too.
With complex ontologies, this is not (easily) possible. No one can possibly remember “Thing/Person/Person of public interest/Singer/21th Century/Madonna”, but everyone can (and will!) tag with “Madonna”.
And it doesn’t matter when other people will tag figures of wood as “Madonna” too, because you can look for “Madonna Music” then. Someone will have tagged it that way.
This is another reason for why tags just work: Because adding metadata is so easy, lots of people can do it, and they will add lots. And “bad” (that is, wrong) tags don’t hurt much (fortunately, tag spamming is still rare).
Still, there is one problem with tags: Due to their limited dimension, it is hard to get an overview of the tag web, even if you have a lots of often used tags. Tags only make sense if you have an consistent, but big set of them. However, I think, this can be solved using metatagging. Why not tagging tags itself?
Say, you want to see all bookmarks about “Music”, but there are bookmarks about “Madonna” that are not tagged itself as “Music”. Still, these pages would be included if the tag “Madonna” was tagged as “Music”.
The problem is now managing these metatags. In spirit of true tagging, this should be done by the same people (and with the same rights) as tagging itself. I’m not sure if this will work; in doubt, one has to limit metatagging. But then, I’ve been proven wrong often enough with respect to tags.
NP: Bright Eyes—Time Code