Halocho #74 - What is Purim all about?

Purim celebrates the redemption from Haman's evil plot to annihilate the Jews. He was not interested in converting them nor in capturing their land - he simply wanted to kill them. All of them; all of us. Purim celebrates being alive, so the Mitzvos of the day are more physical than spiritual. This is the gist of the Al-Hanisim. It is added to bentching (grace after meals) before "Ve'al Hakol" and to davening (prayers) during "Modim". If Al-Hanisim is forgotten there is no need to make amends, though it can be said later (and some Sidurim have relevant instructions.) After hearing the Megila and sending Mishloach Manos and Matonos L'Evyonim the final Mitzva of the day is the Purim meal. Since the highlights of the Purim saga involved wine, there's a Mitzva to drink more than one usually does, so that one falls asleep as a result. However, people who can't control themselves when inebriated, or who risk missing any Mitzva in the process, are forbidden to drink. Source: Kitzur Shulchan Aruch 141:1, 6, 142:6