What is this S/A/B/C/etc. ranking? Is anyone else using it?

Common in gaming culture. Kind of a meme template. S tier is the best tier of something. People make tier lists of all sorts of things with that grading.

Apparently S being a level above A comes from Japanese grading. I’ve been confused by that, too.

It's very common in Japanese-developed video games as well

Just a tier list I think