The commandment is to hear the story of Purim described in the book of Esther (traditionally it is read from the scroll).

Here is a very short summary…(which is not the whole version supplement, just a taster…)

• Once upon a time, between the destruction of the First Temple and the building of the Second Temple, the Jews were almost destroyed.
• In the city of Shushan, Vashti, the Queen of Persia, refuses to obey the order of the King of Persia, Ahasuerus, to appear before his guests. The King then searches the country for a new queen. From among hundreds of applicants, Esther, cousin of Mordechai the Jew, is chosen.
• The King's Prime Minister was an evil man named Haman. Haman, a descendant of the tribe of Amalek, hates the Jews and decides to kill them. He convinces King Ahasuerus to issue an edict, which orders the destruction of all Jews in the land.
• Mordechai pleads with Esther to save the Jewish people by talking to the King. At the risk of her own life, Esther appears before the King without being summoned by him. She reveals her own Jewish identity to the King and reveals Haman's evil plans.
• The King is outraged at Haman, and he issues a decree to make Haman the victim of his own infamous plot. Haman and his sons are killed, and the Jews are saved.

To commemorate this miraculous turn of events, Jews celebrate Purim on the 14th of Adar by reading the Megillah (the story of Purim), enjoying a Purim Feast, sending gifts of food to our friends and the needy, and having great fun.

Ingredient 2. Mishloah Manot

The second of four Purim-related commandments, this custom could be literally translated as the delivery of a portion (of food). It entails sending 2 types of food to one person. Anything beyond that is extra-credit. Of course, one can be creative with this and not be limited to sending the standard Hamentashen, fruit and wine. There are varied (yummy) themes: pasta, bagels and cream cheese, peanut butter and jelly, crackers, cheese and wine, nuts and raisins, etc... One old-day's custom was preparing pastries in the shape of different animals, percussion instruments (for beating Haman), soldiers, and heroes of the Megillah.