Rosh Chodesh--which literally means "beginning of the month" in Hebrew--is the minor holiday that marks the beginning of every Hebrew month. Rosh Chodesh is commemorated with special prayers in synagogue, and in some communities, innovative celebrations.
At the end of months that have 30 days, Rosh Chodesh is observed for two days, on the 30th day of the previous month and the first day of the new month. After months that have 29 days, only the first day of the next month is observed as Rosh Chodesh.
Rosh Chodesh has long been considered a special holiday for women. Some say that this is because the women of Israel did not offer their jewelry for the creation of the Golden Calf. As a result, they were given Rosh Chodesh as a day when they could abstain from work. To this day, some women refrain from some forms of labor on Rosh Chodesh. Others have connected the waxing and waning of the moon to a woman's menstrual cycle. Whatever the reason, Rosh Chodesh has long been a time for Jewish women to gather for a wide variety of activities, from reciting tradition liturgy, to sharing a meal, discussing Jewish ethics, and working for social change.