Tisha B’Av is a Jewish fast day that falls on the 9th day of the month of Av. This is a day to mourn tragedies that have befallen people of Jewish faith in the past on this day.
Five specific calamities, each taking place on the ninth of Av, have marked this day for mourning. The first event occurred when Moses sent 12 scouts to Canaan. 10 of these scouts spoke badly about the land which lead to despair for the rest of the Israelites. Because of this, God marked the day for misfortune in the future.
In 587 BCE the First Temple was destroyed by the Babylonians, and in 70 CE the second temple was destroyed by the Romans. Each of these events happened on the 9th of Av and led to exile for the Jewish people.
On the 9th of Av in 132 CE, at least 100,000 Jews were killed when the Romans defeated the revolt of Bar Kochba and captured the city of Betar. One year later, on the same date the Romans destroyed the City of Jerusalem.
Today Tisha B’Av primarily commemorates the destruction of the first and second temples, but for many people, it is a day to mourn any tragedies that have befallen the Jewish people throughout history. People often observe this holiday by fasting and obtaining from activities such as bathing and physical affection. They also avoid wearing scented perfumes or leather.