Tevet is the tenth month of the Hebrew year, falling in winter, roughly December to January, and aligned in tradition with the sign of Capricorn. It counts twenty-nine days. Its early days complete the festival of Hanukkah, which carries over from Kislev, and its tenth, the fast of the tenth of Tevet, commemorates the beginning of the Babylonian siege of Jerusalem, a minor fast of mourning. The name Tevet, adopted in the Babylonian period, belongs to the depth of winter. The Hebrew calendar is lunisolar, its months set by the moon and kept in step with the solar year by an added month in leap years. These are the observances of the Jewish calendar tradition, in which Tevet joins the last lights of Hanukkah to a winter fast recalling the fall of Jerusalem.
Tevet holds the Tenth of Tevet, a minor fast day traditionally marking the start of the Babylonian siege of Jerusalem that would culminate, roughly two and a half years later, in the city's fall and the Temple's destruction commemorated separately on Tisha B'Av; the Tenth of Tevet is one of four minor fasts, alongside the Seventeenth of Tammuz, the Third of Tishrei (the Fast of Gedaliah) and Tisha B'Av itself, that trace the successive stages of the First Temple's destruction across the calendar year. Hanukkah, beginning in Kislev the month before, typically extends two or three days into the start of Tevet, so the two months' observances overlap at their boundary in most years.