The mourning observances during the Three Weeks are divided into four levels, increasing in intensity:
- From the Seventeenth of Tammuz until the end of Tammuz
- From Rosh Chodesh Av until the week in which Tisha B'Av falls
- The week in which Tisha B'Av falls until the Eighth of Av
- Tisha B'Av itself
Standard Ashkenazic custom, or minhag, restricts the extent to which one may take a haircut, shave or listen to music, though communities and individuals vary their levels of observance of these customs. No Jewish marriages or other major celebrations are allowed during the Three Weeks, since the joy of such an event would conflict with the expected mood of mourning during this time.
Many Orthodox Jews refrain from eating meat during the Nine Days from the first of the month of Av until midday of the day after the fast of Ninth of Av, based on the tradition that the Temple burned until that time.
Time of danger
The Three Weeks are considered historically a time of misfortune, since many tragedies and calamities which befell the Jewish people are attributed to this period. These tragedies include: the breaking of the Tablets of the Law by Moses, when he saw the people worshipping the golden calf; the burning of a Sefer Torah by Apostomus during the Second Temple era; the destruction of both Temples on Tisha B'Av; the expulsion of the Jews from Spain shortly before Tisha B'Av 1492; and the outbreak of World War I shortly before Tisha B'Av 1914, which overturned many Jewish communities.
As a result, some Jews are particularly careful to avoid all dangerous situations during the Three Weeks. These include: going to dangerous places, striking a child or student, undergoing a major operation that could be postponed until after Tisha B'Av, going on an airplane flight that could be postponed until after Tisha B'Av, and engaging in a court case with a non-Jew if it can be postponed until after Tisha B'Av.