Purim is celebrated on the 14th of Adar (late winter/early spring) to commemorate the events recorded in the Book of Esther — the deliverance of the Hebrew people from Haman's plot to destroy them throughout the Persian Empire during the reign of King Ahasuerus (Xerxes I).
The name "Purim" comes from the Hebrew word "pur" (lot), referring to the lots Haman cast to choose the date for his planned massacre. Queen Esther and her cousin Mordecai courageously reversed the decree, and the Hebrew people were saved.
Purim is a joyful celebration involving reading the Book of Esther (the Megillah), feasting, gift-giving, and charity to the poor. It is one of the most beloved feasts in the Hebrew calendar — a reminder of God's providential protection of His covenant people.