Why does the moon change shape?

The moon looks as if it changes shape because sunlight reaches one half of it, and Earth sees that bright half from changing angles. Its rocky body does not stretch or shrink. We are watching different views as the moon moves around us.

When the moon sits near the sun in our sky, its bright face is turned mostly away, so it can seem gone. Later, more of the lit part comes into view, growing from a crescent to a full circle before fading back again.