Purim (Hebrew: פורים) celebrated on the 14th of Adar, is the most joyous holiday on the Jewish calendar. Due to Jerusalem's importance, it celebrates Purim on the 15th despite it not having been surrounded by a wall since the time of Joshua.
It all began 2400 years ago in the ancient Persian Empire.
Haman, the Persian prime minister, persuaded King Ahasuerus to issue a decree ordering the extermination of all the Jews. Haman was a virulent Jew hater.