In the leap year according to the Jewish calendar (there are seven of them in each 19-year cycle), two months of Adar, and the «main» Purim are celebrated in the second Adar, and in the first Purim-Katan (or Small Purim) is celebrated.
Although Little Purim — is a kind of preparation for the main holiday, which will take place in a month. But according to the traditions of the celebration, it still has some differences. So, on the day of Purim-katan they do not read Esther’s scroll, «Tahanun» prayers, and do not wear shelahmunes.
On this day, it is customary to organize a festive feast, of course, not as rich as on Bolshaya Purim, but still not ordinary, and also — it is important to rejoice and have fun in every possible way.
It should also be noted that Purim Katan is not celebrated in all Jewish communities, and the customs of the holiday also differ. By the way, individual holidays celebrated in honor of the miraculous deliverance from enemies or persecution of any city or community also have the same name — Purim-katan —. About a hundred such events are known, although many of them have not been celebrated for a long time.