I keep seeing that quite often, people refer to some sets, head art with word "rare" and that sort of throws me off because in my eyes every set and head is equally rare as only one person owns it.
So what exactly does the "rare art" term mean?

in this sense, if a really good artist made art, but didnt make a lot of art before stopping, then that art is rare. tbashboii selling a set by Vitiek, and that set is rare because im pretty sure its the only set vitiek made, and vitiek is a godly artist.

Alright its clear now, thanks

I believe vitiek made 2-3 sets, but this was the only decent one, the others were from when he first started art.