Why does the moon go through phases?

The Moon has phases because it orbits Earth, which causes the portion we see illuminated to change.

Explanation:

The Moon takes 27.3 days to orbit Earth, but the lunar phase cycle (from new Moon to new Moon) is 29.5 days ... As the Sun sets, the Moon rises with the side that faces Earth fully exposed to sunlight (5).

Answer: it has phase because it orbits and rotates causing the sunlight to hit different parts of the moon making it light up a certain way