Some thoughts:

I remember I would write whole ass essays in the tag section of tumblr. In a way, the tag section conveyed a loud quiet voice—the hashtag had symbolized a liminal space between a fully developed thought and silent indifference.

• Tags represented a more stream of consciousness style method of communication without the typical rule sets of language and punctuation
• An entirely different thought is its own tag
• A drawn out laughter could be a tag
• Great ideas could be a tag
• Some tags were utilitarian, others would be purely reactionary

And most importantly, tags were your own and on your blog only. They could not be transferred every time someone reblogs (unless someone screenshotted them and used it as an image). So unlike captions which could be shared and embedded into the post, tags were an exclusive way to communicate to your community and the people interacting with your blog directly.

Back when I posted my drawings on tumblr in high school, I was kiiinda obsessed with viewing every single reblog of my work to see what kind of tags they added.

The best ones were the tags that commented directly on the work. Something like “#nice” or “#so cool”...something to that extent—it was really great to see. I felt like I was in on a genuine compliment that was directly from the voice inside their heads instead of something filtered you would say out loud...if that makes sense?? And I’m not sure if people put tags with the intention that the OP would even see it.