As they currently are, tags are a giant mess. We've already decided that we won't add genres as a first-class entity of their own (MBS-3738), and previous summits seem to have favored some sort of enhanced tags to represent them. This increases the need for better tag organization.

Danbooru-style image boards use color-coded categories for tags. As an example, one of them has these four:

• artist: the artist who made the particular image, e.g. "clamp"
• copyright: the original work or franchise, e.g. "chobits"
• character: the characters depicted in an image, e.g. "chii"
• general: various other tags describing the image, e.g. "umbrella" or "scan". Some boards divide these further and would e.g. label the latter as a technical aspect.

I think that we could apply these ideas quite well for some of the things we use tags for, such as:

• genres
• media franchises (also see MBS-8273)
• themes, e.g. "love song", "party" etc.
  And possibly other categories such as stylistic elements, as well as unsorted, general tags for everything else.