The Tenth day of the Hebrew month Tevet, known as “Asara b'Tevet”, is a fast day. The fast is observed from morning until night. This year (2015) the fast is today, Thursday, the first of January.
Historcally, the fast commemorates the day that the Babylonians first laid siege to Jerusalem, 423 BCE, cutting it off from the outside world. This not only laid the groundwork for the destruction of the Holy Temple but also caused horrific suffering for the besieged population of Jerusalem, thousands of whom died from starvation and disease.
In recent times, the Chief Rabbinate of Israel chose to observe the Tenth of Tevet as a “General Kaddish Day” for the victims of the Holocaust, many of whom lack identifiable yahrtzeits (anniverseries of their death).
It is a day for personal and national introspection, with the goal of bettering our ways with hopes and prayers for a brighter future.