There are eight different phases or "types" of the moon: new, waxing crescent, first quarter, waxing gibbous, full, waning gibbous, last quarter and waning crescent. These phases repeat themselves approximately every 29.5 days.
During the revolution of the moon around the Earth, the moon reflects the sun's light in various ways depending on its position in the sky. This reflection of light makes the moon appear as if it is changing sizes. "Waxing" and "waning" are two terms used to describe the moon's phases. To "wax" means to increase or to grow; this "growing" refers to the illuminated part of the moon. To "wane," on the other hand, means to shrink or to be diminished; the "shrinking" is in reference to the part of the moon that is lit up. Many cultures have their own names for the full moon that are still referred to colloquially today. For example, January's full moon is referred to as the "wolf moon" in reference to the howling of hungry wolves during this midwinter time. Another well-known example is the "harvest moon" that is observed each September. This moon acquired its name due to this being the time of the year that autumn's crops are usually harvested.