Fix Python – What is the meaning of “Failed building wheel for X” in pip install?

This is a truly popular question here at SO, but none of the many answers I have looked at, clearly explain what this error really mean, and why it occurs.
One source of confusion, is that when (for example) you do pip install pycparser, you first get the error:
Failed building wheel for pycparser
which is then followed by the message that the pa….

Fix Python – How do I install a Python package with a .whl file?

I’m having trouble installing a Python package on my Windows machine, and would like to install it with Christoph Gohlke’s Window binaries. (Which, to my experience, alleviated much of the fuss for many other package installations). However, only .whl files are available.
But how do I install .whl f….