While not one of the major Jewish festivals of the year, Purim does have a number of important mitzvoth associated with it:
With the arrival of Adar, we increase our merriment - have a good time on Purim, dress up in costumes, and enjoy the revelry!
The most important mitzvah of Purim is hearing the reading of Megillah Esther - the story of Esther. The Megillah is read at both the evening and morning services on Purim day.
There are several other additions to the service on Purim: al ha-nissim is added to the Amidah and to the birkat ha-mazon, the blessings following a meal; and Exodus 17:8-16 is read from the Torah.
One should have a festive meal on the afternoon of Purim, where Purim stories and silly songs are shared and enjoyed by all.
Mordechai instructed the Jews of his time that Purim should also be a time of sending portions and gifts to the poor. A minimum of two different kinds of food should be sent to friends for mishloach manot - baskets traditionally given to friends and strangers on Purim. In addition, handing out Mattanot L'evyonim (gifts to the poor) is another mitzvah of Purim.