The changing shapes of the moon that we see are called "phases of the moon" or "lunar phases." These phases occur because of the way the moon orbits around the Earth and reflects sunlight. As the moon moves in its orbit, different portions of its illuminated surface become visible from Earth, resulting in the various phases. The primary phases of the moon are New Moon, Waxing Crescent, First Quarter, Waxing Gibbous, Full Moon, Waning Gibbous, Third Quarter, and Waning Crescent.