Shekalim
When the Holy Temple stood in Jerusalem, each Jew contributed an annual half-shekel to the Temple.
The funds raised were primarily used to purchase cattle for the communal sacrifices. The leftover monies were used for a variety of communal purposes, including providing salaries for the judges and maintenance of the Temple, its vessels, and the city walls.
This annual tax, known as the machatzit hashekel, was due on the 1st of Nissan. One month earlier, on the 1st of Adar, the courts began posting reminders about this Biblical obligation. In commemoration, the Shekalim is the first of four readings added during or immediately before the month of AdarTorah reading of the Shabbat that falls on or before Adar 1 is supplemented with the verses (Exodus 30:11-16) that relate G‑d's commandment to Moses regarding the first giving of the half-shekel.
The Shekalim haftorah (II Kings 11:17-12:17) continues on the same theme, discussing the efforts of King Jehoash (9th century BCE) to earmark communal funds for the upkeep of the first Holy Temple.
(We too give a commemorative half shekel to charity—on the Fast of Esther. Click here for more about this practice.)
"Parshat Shekalim" is the first of four special readings added during or immediately before the month of Adar (the other three being Zachor, Parah and Hachodesh).
The Shekalim reading is also related to the upcoming holiday of Purim. According to the Talmud, Haman's decree was averted in merit of the mitzvah of machatzit hashekel.
Click here for the Shekalim Reading along with commentary and insights.