Part of the mourning period known as "The Three Weeks". During this period, which immediately precedes Tisha B'Av, practices of mourning are increased.
Period of increased mourning for the destruction of the Temple in Jerusalem. For Ashkenazim this extends from the first of Av until the 10th at midday. For Sefardim it extends from the Sunday prior to Tisha b'Av until the end of the 10th of Av.