[What follows is fairly inside-baseball so if you are not particularly into this topic it will probably be somewhat obscure and likely not very interesting, so you are warned!]
What are we to do with this term 'Tags'? It is used in many different places, sometimes to mean the same thing and sometimes something subtly different. This is not surprising about a set of ideas that are morphing right in front of our eyes and ears. So let's look at some examples and compare them.
Let's look at tags in Flickr and tags in Del.icio.us (if you don't know one or the other, you owe it to yourself to look into them.)
Both have tags, but they are different in a subtle way:
In Flickr I am tagging my own stuff (pictures that I’ve uploaded) mostly for other people to find.
In Del.icio.us I am tagging mostly other people’s stuff (links to web pages) for my own benefit, that is organizing links of interest to me.
Look at this:
One way to organize a taxonomy of folksonomies is to notice that there are two dimensions: Whose stuff is being tagged, and for whose benefit. Flickr ends up in the bottom right, and del.icio.us in the top left. But what about the other quadrants?
This organization gives a new way of looking at conventional concepts like folders and directories on personal computers (my stuff/my own benefits) and Web based directories like Yahoo (other people's stuff/other people's benefit.)