Yom Kippur is the most important holiday of the Jewish year: The Day of Atonement, when those of the Jewish faith do not work and attend synagogue services, pray, repent and fast.
Here is some information about the holiday from the Judaism 101 Website: “Most of the holiday is spent in the synagogue, in prayer. In Orthodox synagogues, services begin early in the morning (8 or 9 AM) and continue until about 3 PM. People then usually go home for an afternoon nap and return around 5 or 6 PM for the afternoon and evening services, which continue until nightfall. The services end at nightfall, with the blowing of the tekiah gedolah, a long blast on the shofar.”