The ninth day of the Hebrew month of Av begins tonight (Wednesday, July 29) at sunset. This day marks the anniversary of the destruction of both the First and Second Temples in Jerusalem, in 423 BCE and 69 CE by the Babylonians and the Romans respectively.
(There are a couple of ways to figure the count, so you may sometimes see slightly different dates given.) Throughout Jewish history, many other calamities of note happened or began on this same day. It is observed as a day of fasting and mourning, because it is only through our awareness of where we came from and what we’ve been through that we can continue to move forward and appreciate who we are and who we can become. (More on that in the Thought for the Week.)
The basic observances of the day include:
No eating, drinking, bathing, marital relations, or wearing leather shoes from sunset until nightfall the next night on the next day.
Hearing in the synagogue or reading the book of Eicha (Lamentations).
Refraining from any study of Torah not directly pertaining to the story of the Destructions or the laws of mourning, for Torah study is the truest form of joy.
Giving charity (some say at least the value of the meals we are not eating) to the poor.