The mourning observances during the Three Weeks are divided into four levels, increasing in intensity:[1] Standard Ashkenazic custom, or minhag, restricts the extent to which one may take a haircut, shave or listen to music with instruments.
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 mourning mood during this time.
Isaac Tyrnau (late 14th-early 15th centuries) wrote in his book Minhagim, a record of Austrian customs, that haircuts are not taken and weddings are not celebrated during the Three Weeks.
These prophecies of Jeremiah and Isaiah predict the fall of Jerusalem, unlike most haftarot of the yearly cycle, which reflect the theme of the day's Torah reading.
Many Jewish communities refrain from partaking of poultry, red meat, and wine; wearing freshly laundered clothes; and bathing in warm water.