Yom Kippur (יום כיפור)
Yom Kippur (Hebrew: יוֹם כִּפּוּר or יום הכיפורים) is observed on the 10th day of the Hebrew month Tishrei. Yom Kippur means Day of Atonement. The ten days of repentance (עשרת ימי תשובה) that start with Rosh Hashana (the first day of the Jewish year) culminate with Yom Kippur, considered the day of judgment for the new year.
Yom Kippur's atonement is only for sins between man and G-d, not sins against another person.
Yom Kippur is a day of fasting that starts before sunset on the evening before Yom Kippur and ends after nightfall on the day of Yom Kippur. In Israel, on Yom Kippur, vehicle travel is prohibited, except for emergencies.
Yom Kippur services begin generally at 8 AM and continue until about 1-3 PM. Prayers usually go home for an afternoon nap and return around 4-6 PM for the afternoon and evening services. The services end with the blowing of a long blast on the shofar.
Mention of Yom Kippur in the Torah
Leviticus 23:26-32:
26 And the Lord spoke to Moses, saying:
27 But on the tenth of this seventh month, it is a day of atonement, it shall be a holy occasion for you; you shall afflict yourselves, and you shall offer up a fire offering to the Lord.
28 You shall not perform any work on that very day, for it is a day of atonement, for you to gain atonement before the Lord, your God.
29 For any person who will not be afflicted on that very day, shall be cut off from its people.
30 And any person who performs any work on that very day I will destroy that person from amidst its people.
31 You shall not perform any work. [This is] an eternal statute throughout your generations in all your dwelling places.
32 It is a complete day of rest for you, and you shall afflict yourselves. On the ninth of the month in the evening, from evening to evening, you shall observe your rest day.
ויקרא פרק כג
כו וַיְדַבֵּר יְהוָה, אֶל-מֹשֶׁה לֵּאמֹר.
כז אַךְ בֶּעָשׂוֹר לַחֹדֶשׁ הַשְּׁבִיעִי הַזֶּה יוֹם הַכִּפֻּרִים הוּא, מִקְרָא-קֹדֶשׁ יִהְיֶה לָכֶם, וְעִנִּיתֶם, אֶת-נַפְשֹׁתֵיכֶם; וְהִקְרַבְתֶּם אִשֶּׁה, לַיהוָה.
כח וְכָל-מְלָאכָה לֹא תַעֲשׂוּ, בְּעֶצֶם הַיּוֹם הַזֶּה: כִּי יוֹם כִּפֻּרִים, הוּא, לְכַפֵּר עֲלֵיכֶם, לִפְנֵי יְהוָה אֱלֹהֵיכֶם.
כט כִּי כָל-הַנֶּפֶשׁ אֲשֶׁר לֹא-תְעֻנֶּה, בְּעֶצֶם הַיּוֹם הַזֶּה--וְנִכְרְתָה, מֵעַמֶּיהָ.
ל וְכָל-הַנֶּפֶשׁ, אֲשֶׁר תַּעֲשֶׂה כָּל-מְלָאכָה, בְּעֶצֶם, הַיּוֹם הַזֶּה--וְהַאֲבַדְתִּי אֶת-הַנֶּפֶשׁ הַהִוא, מִקֶּרֶב עַמָּהּ. לא כָּל-מְלָאכָה,
לֹא תַעֲשׂוּ: חֻקַּת עוֹלָם לְדֹרֹתֵיכֶם, בְּכֹל מֹשְׁבֹתֵיכֶם.
לב שַׁבַּת שַׁבָּתוֹן הוּא לָכֶם, וְעִנִּיתֶם אֶת-נַפְשֹׁתֵיכֶם; בְּתִשְׁעָה לַחֹדֶשׁ, בָּעֶרֶב--מֵעֶרֶב עַד-עֶרֶב, תִּשְׁבְּתוּ שַׁבַּתְּכֶם.