What is it called when the moon looks different at different times of the month?

The phenomenon of the moon appearing different at various times of the month is called the lunar phases. This variation occurs due to the changing positions of the Earth, moon, and sun, which affect how much of the moon’s surface is illuminated as seen from Earth. The main phases include the new moon, waxing crescent, first quarter, waxing gibbous, full moon, waning gibbous, last quarter, and waning crescent.