The day's main observances consist of full fasting and asceticism, both accompanied by extended prayer services (usually at synagogue) and sin confessions.

Alongside the related holiday of Rosh Hashanah, Yom Kippur is one of the two components of the High Holy Days of Judaism.

[18] The Mussaf prayer on Yom Kippur includes a section known as the Avodah, where a poem is recited describing this Temple service.

[19] According to Jewish tradition, on Rosh Hashanah God inscribes each person's fate for the coming year into the Book of Life, and waits until Yom Kippur to "seal" the verdict.

[22] Thus, the Yom Kippur prayers contain extended confessions which list varieties of errors and sins, and to which one can add their own missteps, along with requests for forgiveness from God.

[25] According to the Bible, after the golden calf sin, Moses descended from Mount Sinai and broke the Tablets of Stone, which contained the Ten Commandments and symbolized the covenant with God.

[26] After God agreed to forgive the people's sin, Moses was told to return to Mount Sinai for a second 40-day period, in order to receive a second set of tablets.

On this day Moses announced to the people that they had been forgiven; as a result the Torah fixed this date as a permanent holiday of forgiveness.

[32] This is continued to the present day, as recitation of the Thirteen Attributes remains an important part of the Yom Kippur prayers (in Maariv and Neilah).

While many of the observances of Yom Kippur (such as fasting and long prayers) can be difficult, there is also a tradition in which they are interpreted positively, as indications of closeness of God.

Various sources compare the observances of Yom Kippur – fasting, barefootness (not wearing leather shoes), standing (in prayer), particular manners of prayer, even the peace that exists between Jews on this day – with the behavior of angels, suggesting that on Yom Kippur Jews become like angels in heaven, purified and close to God and not limited by physicality.

[37][38] According to the Torah, the Yom Kippur Temple service was commanded in wake of the deaths of Nadab and Abihu on the eighth day of the Tabernacle inauguration.

[54] When the scapegoat was selected on Yom Kippur to symbolically carry the people's sins to the desert, a crimson cord was tied around its horns.

[59] Similarly, the Mishnah describes Yom Kippur as a day on which men and women would once meet each other in the vineyards in order to arrange marriages.

The Talmud records no less than 14 stories attesting to the importance of the day for repairing relationships with one's spouses, parents, children, coworkers, the poor, and other individuals.

[63] The kapparot ritual, in which either money or a chicken is given to charity, is performed by some on Erev Yom Kippur as a means to enhance atonement.

[97] Following the fast, Sephardic Jewish communities traditionally serve a drink made from melon seeds similar to the Turkish sübye.

[100] This is followed by coffee with milk and biscochos (savory ring-shaped cookies), pieces of bread dipped in olive oil and za'atar alongside tomato, and later, chicken cooked with dry quinces or plums.

Other notable additions to Yom Kippur Mussaf in the Eastern Ashkenazic rite include the Unetanneh Tokef and Ten Martyrs poems.

After Ne'ila, Yom Kippur comes to an end with a recitation of Shema Yisrael and the blowing of the shofar,[102] which marks the conclusion of the fast[105] and symbolizes freedom from sin.

The cantor stands with two community members at his sides, and chants the Kol Nidre prayer (Aramaic: כל נדרי, English translation: 'All vows').

[112] This traditional prominence is rooted in the Babylonian Talmud's description of how to attain atonement following the destruction of the Temple in tractate Yoma.

Orthodox liturgies include prayers lamenting the inability to perform the Temple service and petitioning for its restoration, which Conservative synagogues generally omit.

Confession is recited an 11th time by individuals in the Mincha prayer of Yom Kippur eve, before the beginning of the holiday, and in some communities this is repeated by the Chazzan.

Reform synagogues generally experience their largest attendance of the year on Yom Kippur and Rosh Hashanah for worship services.

The prayer philosophy of Reform, as described in the introduction of the movement's High Holy Day prayerbook, Mishkan HaNefesh, is to reflect "varied theological approaches that enable a diverse congregation to share religious experience... with a commitment to Reform tradition, as well as [to] the larger Jewish tradition."

"For more than a century and a half in the Reform Movement," writes Rabbi Lance Sussman, "High Holiday sermons were among the most anticipated events in synagogue life, especially on the eve of Rosh Hashanah and Kol Nidre night.

Over the last few decades, bicycle-riding and inline skating on the empty streets have become common among secular Israeli youths, especially on the eve of Yom Kippur in Tel Aviv.

Such incidents throw into sharp highlight the conflict many Jewish people face between social pressures and personal beliefs on a daily basis.

[126] The examples of Greenberg and Koufax have been followed by numerous athletes, including fellow baseball players Shawn Green, Kevin Youkilis, Brad Ausmus, and Art Shamsky.