Purim is celebrated on the fourteenth day of the month of Adar. Its historical background is found in the Scroll of Esther. We celebrate God’s miracle, which changed the fate of the Jewish people in the times of King Achashveirosh of Persia. The Sofrim, the group of Sages that lived from the time of Ezra to the beginning of the Tannaitic period, issued the ruling that the Megillah, the book of Esther, must be read on the evening of Purim and again the next morning. It is because the Megillah has been considered the equivalent of thanksgiving and praise that Hallel, which is usually said on every festive occasion, is omitted on Purim. In other words, the Megillah takes the place of the Hallel. It is also customary to disguise oneself and put on masks and costumes. A festive meal is eaten during the day.