Summary of Tammuz
Tammuz is the fourth month of the Jewish calendar, which begins the summer season. The three months of this season—Tammuz, Av and Elul—correspond to the three tribes of the camp of Reuben, which include Reuben, Simeon and Gad, who were situated to the south of the Tabernacle.
During the month of Tammuz, Israel sinned by making the golden calf, which resulted in the breaking of the first set of tablets given to Moses by God. That very day, the 17th of Tammuz begins a three-week period—ending on the 9th of Av—which commemorates the destruction of the Holy Temple in Jerusalem.