Why does the moon have phases?

The Moon has phases because of the way it orbits the Earth. As the Moon orbits the Earth, different parts of the Moon are illuminated by the Sun, causing it to appear differently throughout its 29.5 day lunar cycle.

The phases of the Moon begin with the New Moon, where the side facing the Earth is not illuminated. The first visible phase is the Waxing Crescent, where a small sliver of the Moon appears to be illuminated. This is followed by the First Quarter, where half of the Moon appears to be illuminated. The Waxing Gibbous follows, where more than half but not all of the Moon appears to be illuminated. The Full Moon is the next phase, where the entire face of the Moon is illuminated by the Sun. This is followed by the Waning Gibbous, Third Quarter, and Waning Crescent phases.