Purim is a festival that commemorates the deliverance of the Jewish people of the ancient Persian Empire from Haman’s plot to annihilate them, as recorded in the Biblical Book of Esther (Megillat Esther). According to the story, Haman cast lots to determine the day upon which to exterminate the Jews.
Purim is celebrated annually according to the Hebrew calendar on the 14th day of the Hebrew month of Adar (Adar II in leap years), the day following the victory of the Jews over their enemies; as with all Jewish holidays, Purim begins at sundown on the previous secular day. In cities that were protected by a surrounding wall at the time of Joshua, including Shushan (Susa) and Jerusalem, Purim is celebrated on the 15th of the month, known as Shushan Purim. Purim is characterized by public recitation of the Book of Esther (keriat ha-megilla), giving mutual gifts of food and drink (mishloach manot), giving charity to the poor (mattanot la-evyonim), and a celebratory meal (se’udat Purim); other customs include drinking wine, wearing of masks and costumes, and public celebration.
Jewish exiles from the Kingdom of Judah who had been living in the Babylonian captivity (6th Century BCE) found themselves under Persian rule after Babylonia was in turn conquered by the Persian Empire. According to the Book of Esther, Haman, royal vizier to King Ahasuerus planned to kill the Jews, but his plans were foiled by Esther, his queen. Mordecai, a palace official, cousin and foster parent of Esther, subsequently replaced Haman. The Jews were delivered from being the victims of an evil decree against them and were instead allowed by the King to destroy their enemies, and the day after the battle was designated as a day of feasting and rejoicing.
For more information see Wikipedia
