Yom Kippur   

...In the seventh month, on the tenth day of the month, you shall afflict your souls, and you shall not do any work ... For on that day he shall provide atonement for you to cleanse you from all your sins before the L-RD. -Leviticus 16:29-30

Yom Kippur is perhaps the most important holiday of the Jewish year. Many Jews refrain from work, fast and/or attend services on this day. Yom Kippur occurs on the 10th day of Tishri. (Leviticus 23:26).

The name "Yom Kippur" means "Day of Atonement."  It is a day set aside to atone for the sins of the past year. On Yom Kippur, the judgment entered in these books is sealed. This day is the last chance to change the judgment, to demonstrate repentance and make amends.

Yom Kippur atones only for sins between man and G-d, not for sins against another. To atone for sins against another person, you must first seek reconciliation with that person, righting wrongs you committed against them if possible. This must be done before Yom Kippur.

Yom Kippur is a complete Sabbath; no work can be performed. You are supposed to refrain from eating and drinking (even water) on Yom Kippur. It is a complete, 25-hour fast beginning before sunset on the evening before Yom Kippur and ending after nightfall on the day of Yom Kippur. The Talmud also specifies restrictions on washing and bathing, anointing one's body (with cosmetics, deodorants, etc.), wearing leather shoes, and engaging in sexual relations.

As always, any of these restrictions can be lifted where a threat to life or health is involved. In fact, children under the age of nine and women in childbirth (from the time labor begins until three days after birth) are not permitted to fast,  even if they want to. Older children and women from the third to the  seventh day after childbirth are permitted to fast, but are
http://www3.telus.net/public/kstam/en/temple/details/day_of_atonement.htm
permitted to break the fast if they feel the need to do so. People with other illnesses should consult a physician and a rabbi for advice.

Most of the holiday is spent in the synagogue, in prayer. The services end at nightfall, with the tekiah gedolah, a long blast on the shofar.

It is customary to wear white on the holiday, which symbolizes purity and calls to mind the promise that our sins shall be made as white as snow (Is. 1:18). Some people wear a kittel, the white robe in which the dead are buried.