Yom Kippur 2013 is observed on Sept. 13-14, 2013. Known as the Jewish Day of Atonement, Yom Kippur falls on 10 Tishrei 5772 on the Hebrew calendar, which is from sundown on Sept. 13 to nightfall on Sept. 14.
The Day of Atonement is considered the most important day of the Jewish year, as evidenced by the synagogue attendance rate: More people go to temple on Yom Kippur than any other holiday.
Yom Kippur marks the end of the Days of Awe, a 10-day period of teshuvah (Jewish reflection, repentance and return) that begins with Rosh Hashanah, the Jewish New Year.
During the Days of Awe, Jews seeks forgiveness from friends, family and co-workers, a process that begins with Tashlich, the symbolic casting off of sins that is traditionally observed on the afternoon of Rosh Hashanah by throwing bread into a body of water. On Yom Kippur, Jews attempt to mend their relationships with God. This is done, in part, by reciting the Vidui, a public confession of sins. The holiday has the most extensive prayer schedule of the Hebrew calendar and arduous abstinence from food, drink, sexual intimacy and animal-based clothing, such as leather.
All major Jewish holidays, including Yom Kippur, consist of four main prayer services: Ma'ariv, Shacharit, Musaf and Mincha. Yom Kippur, though, is unique. It begins with Kol Nidre, a legal document that is hauntingly chanted and emotionally charged. The Book of Jonah is read during the afternoon prayer service on Yom Kippur day. The Day of Atonement is the only Jewish holiday that includes a fifth prayer service, called Ne'ilah, which is a final plea of repentance before the gates of heaven are said to close. The Ne'ilah service precedes the shofar blowing and the end of the fast.
While Yom Kippur is characterized by solemn fasting and marathon prayers of repentance, it is actually considered the most joyous day of the Jewish year because it commemorates God's forgiveness of the sin of the Golden Calf, the Israelites' slip into idolatry after the giving of the Ten Commandments, and is considered a time to spiritually start anew.