I think my tabs mostly belong to one of two categories:

* Research about a subject (that I didn't close when I continued to the next one)

* "Oh that's interesting, I'll read it later"

I do remember that 10+ years ago I used to have a nice collection of bookmarks, each with relevant tags. Then one day I had to switch browsers due to performance issues, the new browser didn't support tags from the previous one so lost everything. Ended up just keeping tabs open after that and every now and then I just go through them until 500 or so remain.

For the "read it later" scenario I'm aware that there are a lot of services that try to solve that problem, none that I've tried just seem to fit my workflow.