Adar is the twelfth month of the Hebrew year in an ordinary year, falling in late winter toward spring, roughly February to March, and aligned in tradition with the sign of Pisces. It counts twenty-nine days. Adar is the month of Purim, kept on the fourteenth, which celebrates the deliverance of the Jews of Persia recounted in the Book of Esther, a joyous festival of feasting, gifts, costumes, and the reading of the scroll; the tradition holds that when Adar enters, joy is increased. In a leap year a second Adar is added and Purim is kept in it. The Hebrew calendar is lunisolar, kept in step with the solar year by this added month. These are the observances of the Jewish calendar tradition, in which Adar is the most festive turn toward spring.
Adar, in a regular (non-leap) year, holds Purim on the fourteenth, commemorating the deliverance of the Jews of the Persian Empire from a planned massacre as recounted in the book of Esther, marked by the public reading of that book, gift-giving, charity to the poor, and festive meals. In a leap year, when a second Adar is intercalated, Purim moves to the fourteenth of Adar II, the added month taking over the regular Adar's festivals while the earlier Adar I, sometimes called Adar Rishon, carries none of its own, a rule the Talmud fixes explicitly (Megillah 6b) to keep Purim as close as possible to the following month of Nisan and the Passover season.