Pesach, known as Passover in English, is a major Jewish spring festival, commemorating the Exodus from Egypt over 3,000 years ago. The ritual observance of this holiday centers around a special home service called the seder (meaning "order") and a festive meal; the prohibition of chametz (leaven); and the eating of matzah (an unleavened bread). On the eve of the fifteenth day of Nisan in the Hebrew calendar, we read from a book called the hagaddah, meaning "telling," which contains the order of prayers, rituals, readings and songs for the Pesach seder. The Pesach seder is the only ritual meal in the Jewish calendar year for which such an order is prescribed, hence its name.