Image mapped version of earlier “swap” moon phases graphic. Mouse over each element for descriptive captions. Used Summer HTML Image Map Creator
We see moon phases because of the relative motion of the Earth and Moon and our perspective from the surface of the Earth. Changing the perspective is the easiest way to see what is happening. Here is a 4 minute narrated video that may help you to visualize the mechanics.
Screen capture of Solar Walk software demonstrating how the moon phases “work”