Purim (; Hebrew: פּוּרִים Pūrīm, lit. 'lots'; see Name below) is a Jewish holiday which commemorates the saving of the Jewish people from annihilation at the hands of an official of the Achaemenid Empire named Haman, as it is recounted in the Book of Esther (usually dated to the 5th century BCE).

Haman was the royal vizier to the Persian king Ahasuerus (Xerxes I or Artaxerxes I; Khshayarsha and Artakhsher in Old Persian, respectively). His plans were foiled by Mordecai of the tribe of Benjamin, and Esther, Mordecai's cousin and adopted daughter who had become queen of Persia after her marriage to Ahasuerus. The day of deliverance became a day of feasting and rejoicing among Jews.

According to the Scroll of Esther, "they should make them days of feasting and gladness, and of sending portions one to another, and gifts to the poor". Purim is celebrated among Jews by:

• Exchanging gifts of food and drink, known as mishloach manot
• Donating charity to the poor, known as mattanot la-evyonim
• Eating a celebratory meal, known as se'udat Purim
• Public recitation of the Scroll of Esther (Hebrew: קריאת מגילת אסתר, romanized: Kriat megillat Esther), or "reading of the Megillah", usually in synagogue
• Reciting additions to the daily prayers and the grace after meals, known as Al HaNissim

Other customs include wearing masks and costumes, public celebrations and parades (Adloyada), and eating hamantashen (transl. "Haman's pockets"); men are encouraged to drink wine or any other alcoholic beverage.

According to the Hebrew calendar, Purim is celebrated annually on the 14th day of the Hebrew month of Adar (and it is celebrated in Adar II in Hebrew leap years, which occur every two to three years), the day following the victory of the Jews over their enemies, the 13th of Adar, a day now observed with the fast of Esther. In cities that were protected by a surrounding wall at the time of Joshua, Purim was celebrated on the 15th of the month of Adar on what is known as Shushan Purim, since fighting in the walled city of Shushan continued through the 14th day of Adar. Today, only Jerusalem and a few other cities celebrate Purim on the 15th of Adar.