A: The so called Luna, half moon, or sickle of the moon, also waning and waxing moon, is a sign of fertility, related to life and death, and thus a popular symbol in many religions. It pinpoints changing seasons, ebb and tide (and related inundations as harbingers of fertility), and the feminine menstrual cycle.
Crescent moons are often worn to bring luck and wealth. In some cultures, they're believed to be a protection against negativity; in Japan, for example, dangling them from the rearview mirrors of cars is thought to keep away evil spirits from your space