I don't think tags are good enough to categorize data. Tags lack information what is being tagged. When it's clear what's tagged then they work. On twitter for

I don't think tags are good enough to categorize data. Tags lack information what is being tagged. When it's clear what's tagged then they work. On twitter for instance it's the topic you're speaking about. What you really want is a property system like wikidata. Think about a music program you want to write. You want to find all artists that music files on this computer have and when the user clicks on an artist find all the music that belongs to this artist.