On the 10th of Tishrei of the year 2449 from creation, 82 days after the people of Israel betrayed their newly entered covenant with G-d by worshipping a Golden Calf and after Moses twice spent 40 days atop Mount Sinai pleading on their behalf, "G-d restored His goodwill with the Jewish people gladly and wholeheartedly, saying to Moses 'I have forgiven, as you ask', and gave him the Second Tablets" -- thereby establishing the day as a time for atonement, forgiveness and teshuvah for all generations.
Yom Kippur is the holiest day of the year -- the day on which we are closest to G-d and to the quintessential core of our own souls. It is the "Day of Atonement" -- "For on this day He will forgive you, to purify you, that you be cleansed from all your sins before G-d" (Leviticus 16:30).
For twenty-six hours, from several minutes before sunset on Tishrei 9 to after nightfall on Tishrei 10, we "afflict our souls": we abstain from food and drink, do not wash or anoint our bodies, do not wear leather shoes, and abstain from marital relations.
When the Holy Temple stood in Jerusalem, the Yom Kippur service included the High Priest's entry into the "Holy of Holies" to offer the ketoret -- the only time that anyone entered the Temple's innermost chamber -- and the "casting of lots" over two goats, one to be offered to G-d and the other to carry off the sins of Israel to the wilderness. Today, we spend the day in the synagogue garbed in a white garment called a kittel to resemble the sin-free angels and to waken thoughts of repentance by reminding us of the day of our death. In the course of the day we hold five prayer services: Maariv, with its solemn Kol Nidrei service, on the eve of Yom Kippur; Shacharit; Musaf, which includes a detailed account of the Temple service; Minchah, which includes the reading of the Book of Jonah; and Ne'illah, the "closing of the gates" service at sunset. We say the Al Chet confession of sins ten times, and recite Psalms every available moment.
The day is the most solemn of the year, yet an undertone of joy suffuses it: a joy that revels in the spirituality of the day and expresses the confidence that G-d will accept our repentance, forgive our sins, and seal our verdict for a year of life, health and happiness. When the closing Ne'illah
service climaxes in the resounding cries of "Hear O Israel... G-d is one" and a single blast of the shofar, the joy erupts in song and dance (a Chabad custom is to sing the lively niggun known as "Napoleon's March"), followed by the festive after-fast meal, making the evening following Yom Kippur a Yom Tov (festival) in its own right.
The 10-day period beginning on Rosh Hashanah and ending on Yom Kippur is known as the "Ten Days of Repentance"; this is the period, say the sages, of which the prophet speaks when he proclaims (Isaiah 55:6) "Seek G-d when He is to be found; call on Him when He is near." Psalm 130, Avinu Malkeinu and other special inserts and additions are included in our daily prayers during these days.
The Baal Shem Tov instituted the custom of reciting three additional chapters of Psalms each day, from the 1st of Elul until Yom Kippur.
On Yom Kippur the remaining 36 chapters are recited, thereby completing the entire book of Psalms. Click below for the break-down of the Psalms.
Once a month, as the moon waxes in the sky, we recite a special blessing called Kiddush Levanah, "the sanctification of the moon," praising the Creator for His wondrous work we call astronomy.
Kiddush Levanah is recited after nightfall, usually on Saturday night. The blessing is concluded with songs and dancing, because our nation is likened to the moon—as it waxes and wanes, so have we throughout history. When we bless the moon, we renew our trust that very soon, the light of G‑d's presence will fill all the earth and our people will be redeemed from exile.
Though Kiddush Levanah can be recited as early as three days after the moon's rebirth, the kabbalah tells us it is best to wait a full week, till the seventh of the month. When sanctifying the moon of the month of Tishrei, it is customary to wait till the night after Yom Kippur.
Once 15 days have passed, the moon begins to wane once more and the season for saying the blessing has passed.