Tonight begins the 17th of Tammuz, one of the minor fast days on the Hebrew calendar, and the beginning of the “3 weeks” leading up to Tisha b’Av.
On minor fast days, we refrain from eating and drinking from sunup to sundown (so the fast is a daytime fast, on Tuesday). Some authorities state that one may not eat from rising in the morning, while others state that one may eat on rising, before sunrise, if they went to bed with that intention the night before.
We add to our ritual on fast days by reading Torah in the morning, and both Torah and Haftarah in the afternoon, and by adding two prayers to the liturgy: Aneinu, during the Amidah, and Avinu Malkenu, following the Amidah.
According to tradition, five tragic events occurred on 17 Tammuz:
1) Moses broke the tablets containing the 10 Commandments when he descended from Mt. Sinai (Exodus 32:19);
2) The regular daily sacrifice was abolished;
3) The Romans breached the walls of Jerusalem during the siege of the Second Temple (according to the Jerusalem Talmud, the Babylonians breached the wall of Jerusalem during the siege of the First Temple, but the destruction of the Second Temple is the more serious disaster);
4) The wicked Apostomos burned a Torah scroll;
5) Through the wickedness of some Jews, an idol was placed in the Temple, and this caused the destruction of the Temple and our exile.
(Source: Kitzur Shulhan Aruh, Chapter 121)
The three week period leading up to Tisha b’Av is a semi-mourning period. During this time, public celebrations (e.g., weddings, concerts) are to be avoided, and some refrain from haircuts. Another custom is not to eat any meat during this period, except on Shabbat or at a feast held on the occasion of performing a religious duty.
During the first 9 days of Av, tradition teaches that we are more restrictive in what we may do, limiting our actions more closely to those restrictions during a period of mourning.