A mnemonic for the eight moon phases. The letters stand for New, Crescent, Quarter, Gibbous, Full. Read forward (NCQGF) for the waxing half of the cycle, then reverse (FGQCN) for the waning half: New Moon → Waxing Crescent → First Quarter → Waxing Gibbous → Full Moon → Waning Gibbous → Last Quarter → Waning Crescent.