Tags are simply free-form keywords people have used to describe their posts. I never could figure out how to create the perfect categorization system for MetaFilter, but this is a great bottom-up way of organizing everything that has ever been posted to MetaFilter. Feel free to plunge into the archives by clicking any phrase that interests you. The larger a word is, the more times it has been used to tag a thread at MetaFilter.

Below are the 150 most often used tags on MetaFilter. (Ask MetaFilter also has a popular tags page)