Judaism observes 12 major holidays. Each begins at sunset and extends to nightfall at the end of the holiday. The most commonly celebrated by American Jews are Passover, which takes place in March or April and lasts for eight days; Rosh Hashanah, the Jewish New Year, in September or October; the Day of Atonement, also called Yom Kippur, in September or October; Sukkot in September or October; Hanukkah, which lasts for eight nights, in November or December; and Purim in February or March. The High Holy Days are the 10-day period beginning with Rosh Hashanah and ending with Yom Kippur. Judaism uses a lunar/solar calendar, so the dates of each holiday move each year. The year of the Jewish calendar (for example, 2006 ushered in the year 5767) represents the number of years since creation.