system
A chat on subreddit /r/pcmasterrace
human
Literally groups of tabs. So rather than having each tab in its own separate menu slot, there are many tabs contained within one slot.

It can help organize large quantities of tabs, but it also requires 2 clicks instead of 1 to get to the page you want.
gpt
Not sure why that would be any better than just bookmarking the url and keeping the bookmark folder organized.