It's in the detail

One of the big questions for a writer is how much detail and which detail do you highlight? What is the function of detail?
Detail gives a description and provides facts but more than that it gives insight into the POV's state of mind.
Two characters looking at the same thing will notice different details. A character whose mood has changed will notice different details. Details help to ring the changes.
Where one character notices the flaking bits of paint and the worn carpet, another sees the...