There's an incessant confusion about what an Affordance is in software design. This is a quick heuristic and justification for why it matters.
The book "the design of everyday things" by Don Norman deals with this for design. I think he even coined the term?
Yep, I think he actually coined the term signifiers while pleading for the the same distinction I'm trying to make. James J Gibson coined the term affordances though as far as I know.