The three weeks that begin on the 17th of Tamuz and end on Tisha B’Av are a period of mourning for the Jewish people. It was during this period that both of our Holy Temples were destroyed.
There are two periods within these three weeks. During the period beginning from 17th of Tamuz until the end of the month of Tamuz (a period of twelve days) the mourning is not as intense. The mourning during the final nine days, beginning with the first of Av until Tisha B’Av, is intensified and many additional practices of mourning are added. (This is according to Ashkenazic practice. According to Sefardic practice, the mourning is only intensified during the actual week in which Tisha B'Av falls.)
During the first twelve days the following practices are observed:
- We do not perform weddings.
- We do not make the blessing shehechyanu. We therefore avoid purchasing or wearing new garments which require this blessing during this period.
- We do not shave or get a haircut.
- We do not listen to instrumental music.
During the final nine days we continue to follow these restrictions in addition to which we add the following practices:
- We do not eat meat or drink wine except on Shabbos.
- We do not do construction when its primary purpose is pleasure (such as building a swimming pool) or aesthetic (such as painting).
- We avoid pleasurable bathing during this period.
- We do not launder clothing during this period nor do we wear fresh clothing (except for Shabbos).
- We do not trim our fingernails during this period.
There are many leniencies that can be relied upon with regard to these restrictions in cases of significant difficulty. In any such case, one should consult a competent rabbi.