It’s not a physical thing, but it looks like a physical thing.
I cringe to think of the amount of articles and time wasted with the ’s’ word, whilst never mentioning the team or thinking that were involved with the iPhone project.
iOS used references from the real world, because it was “a clever way to show information by … interacting with (information) in a physical way.”
To solve complex information design problems and introduce users to a new paradigm of interaction, a lot of iOS was hacked together by industrial designers, thinking like industrial designers. And it worked.