Purim is a joyous Jewish celebration which occurs on the fourteenth day of the month of Adar in the Hebrew calendar beginning at sunset. According to the Book of Esther (the Megillah), the king of Persia, Ahasuerus, was nearly convinced to kill all the Jews in his land. Ahasuerus' chief advisor Haman despised Jews, especially a man named Mordechai who had refused to bow before Haman. Mordechai's niece, Esther, was Ahasuerus' queen. Haman wanted to punish all Jews for Mordechai's actions and convinced Ahasuerus of his position. Ahasuerus, unaware that his queen was Jewish, accepted Haman's plan to cast lots, or Purim, to determine a day for murdering the Jews. Esther intervened on behalf of her people by telling the king that she was Jewish. Upon hearing this, Ahasuerus ordered Haman's death instead and Mordechai assumed Haman's position as chief advisor.
During Purim, the Book of Esther is read aloud in the synagogue. When Haman's name is mentioned, the listeners stamp their feet, boo and hiss and make noise with graggers.