I know what they are but... not much more'n that. They're kinda legends where I'm from. Old stories what only some people know about. An infinity stone is said to have been made at the start of the universe, an' all of 'em can bend one part of reality.

I know there are more than one, but not how many or what all they can do.

...Man's name was Ego. The Celestial. And he didn't so much as kill me as beatin' 'im left me in a place where I'd die real unpleasantly. [But it was him or Peter, and he'd obviously choose Peter.] My boy did most of it.

It was complicated. Big long story. It's own kinda dramatics.