In the Mishnah the recitation of a benediction on the reading of the Megillah is not yet a universally recognized obligation. The Talmud (a later work), however, prescribed three benedictions before and one after the reading. The Talmud added other provisions. For example, the reader is to pronounce the names of the ten sons of Haman (Esth. ix. 7-10) in one breath, to indicate their simultaneous death. The congregation was to recite aloud with the reader the verses ii. 5, viii. 15-16, and x. 3, which relate the origin of Mordecai and his triumph.
The Megillah is read with a traditional chant differing from that used in the customary reading of the Torah. In some places, however, it is not chanted, but is read like a letter, because of the name "iggeret" (epistle) which is applied (Esth. ix. 26, 29) to the Book of Esther. It has been also customary since the time of the Geonim (early medieval era) to unroll the whole Megillah before reading it, in order to give it the appearance of an epistle. According to Jewish law the Megillah may be read in any language intelligible to the audience.
According to the Mishnah (Meg. 30b), Ex. xvii. 8-16, the story of the attack on the Jews by Amalek, the progenitor of Haman, is also to be read.
Purim gave rise to many religious compositions, some of which were incorporated into the liturgy. These include a large number of hymns intended for the public service. As well, other writings (dramas, plays, etc.) intended for general edification, both in Hebrew and in other languages, have been composed.
The Book of Esther prescribes "the sending of portions one to another, and gifts to the poor." This became in the course of time one of the most prominent features of the celebration of Purim. Jews send gifts of food, especially pastries, to one another; and the poor were made recipients of charity. In the synagogue regular collections were made on the festival, and the money was distributed among the needy. No distinction was to be made among the poor; any one who was willing to accept, even a non-Jew, was to be allowed to participate. It was obligatory upon the poorest Jew, even on one who was himself dependent on charity, to give to other poor -- at least to two people. In some congregations it is customary to place a charity box in the vestibule of the synagogue.
The national rather than the religious character of the festival made it appear appropriate to celebrate the occasion by feasting. Hence it was the rule to have at least one festive meal, called Seudat Purim, toward the evening of the 14th. Jews developed special pastries for this holiday; cakes were shaped into special forms and were given names having some symbolic bearing on the historical events of Purim. Thus the Jews of Germany eat Hamantaschen and Hamanohren (in Italy, orrechi d'Aman), Kreppchen, Kindchen, etc.
The jovial character of the feast was illustrated in the saying of the Talmud (Meg. 7b) that one should drink on Purim until he can no longer distinguish "Cursed be Haman" from "Blessed be Mordecai," a saying which was codified in the authoritative code of Jewish law, the Shulkhan Arukh. While Jews have long been noted for a lack of alcohol abuse, drunkenness was licensed on this holiday. In response, later rabbis, worried about the abuse of this rule, developed less literal ways to understand this invitation, and effectively pushed a message of moderation. Merry-making was encouraged; yet total intoxication was condemned.
Many kinds of merry-making and mockery have been indulged in on Purim, so that among the masses it has become almost a general rule that "on Purim everything is allowed", even transgressions of a Biblical law, such as the appearance of men in women's attire and vice versa, which is strictly prohibited in Deut. xxii. 5. The traditional tunes of prayers sung in the synagogue are also sometimes altered, always in deliberately humorous ways.
The custom of masquerading on Purim was first introduced among the Italian Jews about the close of the fifteenth century under the influence of the Roman carnival. From Italy this custom spread over all countries where Jews lived, except perhaps the Orient. The first among Jewish authors to mention this custom is Judah Minz (d. 1508 at Venice) in his Responsa, No. 17, quoted by Isserles on Orah Hayyim, 696:8. He expresses the opinion that, since the purpose of the masquerade is only merrymaking, it should not be considered a transgression of the Biblical law regarding dress. Although some rigorous authorities issued prohibitions against this custom, the people did not heed them, and the more lenient view prevailed. The custom is still practiced today amongst religious Jews of all denominations, and among both religious and non-religious Israelis.
In Israel there are Purim parades, and men, women, boys and girls frolic publicly in costumes and masks, and indulge in all kinds of jollity.
A depiction of a Purim "Gragger" (a "noise maker" when it is spun by hand) usually made of wood and only used when Haman's name is mentioned.Indeed, Purim was an occasion on which much joyous license was permitted even within the walls of the synagogue itself. As such may be reckoned the boisterous hissing, stamping, and rattling, during the public service, at the mention of Haman or his sons, as well as the whistling at the mention of Mordecai by the reader of the Megillah. This practise traces its origin to French and German rabbis of the thirteenth century, who, in accordance with a passage in the Midrash, where the verse "Thou shalt blot out the remembrance of Amalek" (Deut. xxv. 19) is explained to mean "even from wood and stones," introduced the custom of writing the name of Haman, the offspring of Amalek, on two smooth stones and of knocking or rubbing them constantly until the name was blotted out.
Ultimately, however, the stones fell into disuse, the knocking alone remaining. Some wrote the name of Haman on the soles of their shoes, and at the mention of the name stamped with their feet as a sign of contempt; others used for the same purpose a rattle--called "gregar" (from Polish grzégarz), and producing much noise--a custom which is still observed by the Russo-Polish Jews. Some of the rabbis protested against these uproarious excesses, considering them a sinful disturbance of public worship, but did so in vain. The custom of using noisemakers in synagogue on Purim is now almost universal.
Burning of Haman's effigy
Outside the synagogue the pranks indulged in on Purim by both children and adults have been carried even to a greater extreme. Some of them date from the Talmudic period . As early as the fifth century, and especially in the geonic period (9th and 10th cent.), it was a custom to burn Haman in effigy on Purim.
In Italy the Jewish children used to range themselves in rows, and pelt one another with nuts; while the adults rode through the streets with fir-branches in their hands, shouted, or blew trumpets round a doll representing Haman and which was finally burned with due solemnity at the stake. In Frankfort-on-the-Main it was customary to make a house of wax wherein the figures of Haman and his executioner, also of wax, were placed side by side. The whole was then put on the almemar, where stood also the wax figures of Zeresh, the wife of Haman, and two guards--one to her right and the other to her left--all attired in a flimsy manner, and with pipes in their mouths. As soon as the reader began to read the Megillah the house with all its occupants was set on fire to the enjoyment of the spectators.
These customs often aroused the wrath of Christians, who interpreted them as a disguised attempt to ridicule Jesus and the cross and issued prohibitions against them; e.g., under the reign of Honorius (395-423) and of Theodosius II. (408-450; comp. Schudt, l.c. ii. 309, 317, and Cassel, l.c.). The Rabbis themselves, to avoid danger, tried to abolish these customs, often even calling the magistracy to their aid, as in London in 1783. This custom is no longer practiced.
Fasting before and after Purim
The Fast of Esther, celebrated before Purim, on the 13th of Adar, is not an original part of the latter, nor was it later instituted "in commemoration of the fasting of Esther, Mordecai, and the people", since this fasting fell, according to rabbinical tradition, in the month of Nisan and lasted three days. The first who mentions it is R. Aḥa of Shabḥa (8th cent.) in "She'eltot," iv.; and the reason there given for its institution is based on an arbitrary interpretation of Esth. ix. 18 and Meg. 2a, "The 13th was the time of gathering," which gathering is explained to have had also the purpose of public prayer and fasting. Some, however, used to fast three days in commemoration of the fasting of Esther; but as fasting was prohibited during the month of Nisan the first and second Mondays and the Thursday following Purim were chosen. The fast on the 13th is still commonly observed; but when that date falls on a Sabbath the fast is put back to Thursday, Friday being needed to prepare for the Sabbath and the following Purim festival.
In leap-years on the Hebrew calendar, Purim is celebrated in the second month of Adar, but by the Karaites in the first. The respective days of the first Adar being then called "Purim Katan" (Little Purim), for which there have been set forth certain observances similar to those for Purim proper, with the exception of reading the Megillah, sending gifts to the poor, and fasting on the 13th of the month. The distinctions between the first and the second Purim in leap-years are mentioned in the Mishnah (Meg. i. 46b; comp. Orah Hayyim, 697).
Many cities have until recently had local "Purims", also called "Purim Katan", all commemorating the deliverance of the local community from a particular antisemitic ruler or group. The best known is Purim Vintz, traditionally celebrated in Frankfurt am Main, Germany, one week after the regular Purim. This commemorates the Fettmilch uprising (1616-1620), in which one Vincenz Fettmilch attempted to exterminate the Jewish community  (http://www.sehepunkte.historicum.net/2002/07/3792.html). According to some sources, the influential Rabbi Moses Sofer (the Hatam Sofer), who was born in Frankfurt, celebrated Purim Vintz every year, even when Rabbi in Pressburg.