הלכה אויף אסתר 8:16

Praised be the Creator and Glorified be the Designer, Who has caused us to inherit a hidden and precious thing of desire, wonderful wisdom, "For the Jews there was Light;"¹Ester 8:16 light is Torah, to labor in it and to heed to it.

In the morning [it is proper] to get up early to go to the synagogue. After the Shemoneh Esrei, half-kaddish is said. We call up three persons for the Torah-reading of Parashas Vayavo Amalek [And Amelek came] (Ex. 17:8), after which half-kaddish is said. After the seifer Torah is placed in the Ark, the Megillah is read. After the last berachah [over the Megillah], in the morning, we do not say Asher heini [Who annuls the counsel of the nations]. After concluding the berachah with hakeil hamoshia [the God Who brings salvation] we say Shoshanas Yaakov [The rose of Jacob] etc. then Ashrei, Uva leTzion, Full-Kaddish including Tiskabbeil. You should not take off the tefillin until after the reading of the Megillah, because in the Megillah it is written, Vikar [and honor] (8:16), and [our Rabbis] expound that this refers to the tefillin. If there is a bris, it is performed before¹³According to Pri Chadosh and Vilna Gaon, the Megillah is read before the bris. (Mishnah Berurah 693:12) the reading of the Megillah, because it is written vesason [gladness], which refers to bris milah.

One is obligated to be intoxicated on Purim to the point where he does not know [the difference] between "accursed is Haman" and "blessed is Mordechai". Rema: Some say it is not necessary to become drunk so much, but rather to drink more than he is used to (Kol Bo), and to fall asleep, and while he sleeps he does not know [the difference] between "accursed is Haman" and "blessed is Mordechai" (Maharil). [There is no difference on Purim] between one who has more and one who has less, as long as his heart is directed to heaven. One should not fast on Purim, except for a fast for a [bad] dream, and see earlier Siman 568 and Siman 570. There are those who have the custom to dress in Shabbat/Yom Tov clothes on Purim, and that is correct (Maharil). We have the custom to make the Purim meal after the afternoon prayer, and pray the evening prayer at night. We pray the afternoon prayer while most of the day remains, and most of the meal needs to be during the day (Minhagim). And it should not be like those who have the custom to start close to evening, and most of the meal happens during the night of the 15th. When Purim falls out on Friday, they should have the meal in the morning because of honor for the Sabbath (Minhagim). And one who wants to [have his meal] every [Purim] in the morning is allowed to (T"H). Some say that there is [significance] to eating seeds on Purim as a remembrance for the seeds that Daniel and his friends ate in Babylonia (Kol Bo). It is good to delve a bit in Torah before one begins the meal, and a support for that is (Esther 8:16) "The Jews had light and happiness...", which we learn out "radiance" - that's Torah (Mahariv). One is obligated to drink a little and be a little happy on two days, the 14th and the 15th (Minhagim), and so is the custom. And some say that if one causes damage to his fellow through his happiness on Purim, he is exempt from restitution (Terumat HaDeshen, Part I 110). And see Terumat HaDeshen Laws of Damages.