What are tags & Add-a-tag?

I noticed add-a-tag on a thread from today. There are two add-a-tag entries. Clicking around a bit, I see it’s part of the tags list but it isn’t clear what any of this is.

Image of the tags:
Imgur: The magic of the Internet

Tags are meant to be used as subcategories, primarily. For instance, in Cafe Society, you might have tags like: Food, TV Show, Movie, Art, Music, etc. It allows you to keep category count down while allowing people to still filter down to their particular areas of interest for browsing or searching. A topic can even have multiple tags applied to it.

Whether tags are enabled and whether standard users can create them seem to be configurable in discourse. My guess is that tags are enabled here (I can select them on topic creation), but adding them is disabled for non-admin types. Since all of the current tags appear to be silly, my guess is that one of the admins is playing around with them (or perhaps those handful of level 3 users can create them). Either way, they don’t appear to be useful here at this time.

Yes.
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