The Moon does not make its own light; it reflects the light from the Sun
The Sun continuously illuminates half of the Moon’s surface, but varying amounts of it are visible from Earth at any moment. Changes in visibility of the Moon’s surface follow a predictable pattern called the lunar cycle.
The positions of the Sun, Earth, and Moon as they move through space cause the lunar phases to occur to viewers from Earth. The Moon revolves around the Earth about every 28 days.The lunar phases occur in order: new moon, waxing crescent, first quarter, waxing gibbous, full moon, waning gibbous, third quarter, waning crescent