Don Norman, the acclaimed author of the book, The Design of Everyday Things, defined the concept of affordance as “perceivable action possibilities, i.e., only actions which users consider possible.”
He believes good designs should have affordance. For example, a well-designed door can clearly indicate if you should push or pull without the words written on it.
I found the best-designed ads to have the affordance quality as well.The only perceivable action after seeing this ad by KitKat?
Take a break, have a KitKat!