The Ten Days of Repentance (Hebrew: עשרת ימי תשובה, Aseret Yemei Teshuva) are the first ten days of the Jewish month of the Hebrew month of Tishrei, usually sometime in the month of September, beginning with the Jewish holiday of Rosh Hashanah and ending with the conclusion of Yom Kippur.
During this time it is "exceedingly appropriate" for Jews to practice Teshuvah (literally: "returning" or "repentance") which is examining one's ways, engaging in repentance and the improvement of their ways in anticipation of Yom Kippur. A "penitant" is referred to as a baal teshuva ("master [of] repentance"). This repentance can take the form of early morning prayers, known as selichot, which capture the penitential spirit appropriate to the occasion, fasting, charity, acts of Hesed ("loving-kindness"), or self-reflection.
The first two days of the Ten Days of Repentance are on Rosh Hashanah. One of those days may occur on a Shabbat as well, making that day of Rosh Hashanah on which Shabbat occurs stricter in observance, meaning the observances of Shabbat are followed than a Rosh Hashanah that occurs on any other day but Shabbat (Saturday). When Rosh Hashanah occurs on a Shabbat a few additional prayers in the mahzor ("prayer book") are added as well as excluded in keeping with the combined theme of a Rosh Hashanah and Shabbat combination.
The third day is always Fast of Gedalia, it follows Rosh HaShanah. It is a half day fast, meaning it is only observed from dawn of the third day until dusk of that same day.
After Rosh Hashanah ends and before Yom Kippur starts the next notable day is the special Shabbat that has its own name Shabbat Shuvah ("Sabbath [of] Return") meaning the Sabbath devoted to "teshuva" which means "repentance" in Judaism.
The tenth day is the last and it is always the serious Biblically mandated fast of Yom Kippur. Leviticus 23:27 decrees that Yom Kippur is a strict day of rest and of fasting. Yom Kippur can also fall out (meaning be observed) on a Shabbat, one of the rare times when fasting is allowed on that day. Even when it is on a regular weekday, Yom Kippur is still observed as a "Shabbat" because in the Torah it is referred to as a שבת שבתון "Sabbath [of] Sabbaths" Leviticus 23:32.
Three of the main observances are themes that are repeated in both the Rosh Hashanah and Yom Kippur prayer services and printed in every mahzor ("holiday prayer book") of those two holy days: "Repentance, Prayer and Charity (teshuva, tefila, tzedaka) remove the evil decree":[1]
"In almost all editions of the Rosh Hashanah and Yom Kippur machzor, the words ותשובה ותפלה וצדקה repentance, prayer, and charity, are crowned in smaller type with the words [respectively] צום קול ממון, fast, voice, money. These superscripts are meant to indicate that sincere repentance includes fasting, prayer recited in a loud voice, and donations to charity.[2]There are many observances, customs, rituals and prayers said and performed on Rosh Hashanah, such as:
Fasting is done partially only on Fast of Gedalia and for the full day of Yom Kippur. Money in any form is not handled or carried on Jewish holidays according to Jewish law, but promises to make donations are allowed.
In contemporary Judaism, many congregations offer a Selichot service near midnight on the Saturday night preceding the Ten Days of Repentance. This, often short, prayer service serves as a preamble to the High Holy Days (Yom Kippur in particular). The service itself comprises prayers of atonement, the liturgy of which may be found in many machzorim (prayer books for the High Holy Days) or in special prayer books or pamphlets known as "slechot."
Shabbat Shuvah ("Sabbath [of] Return") refers to the Shabbat that occurs during the Ten Days of Repentance between Rosh Hashanah and Yom Kippur. The Jewish calendar is so designed that only one Shabbat can occur between these dates. This Shabbat is named after the first word of the Haftarah Hosea 14:2-10 and literally means "Return!" It is perhaps a play on, but not to be confused with, the word Teshuvah (the word for "repentance") which is the leitmotif of Ten Days of Repentance.
Some Jews and communities have the custom of performing Kapparos during a weekday, a ritual in which either a chicken or money is swung over one's head usually three times as a symbolic atonement by the chicken or the money "assuming the sins" of the one performing the ritual. This custom is not required by the Torah.
On Yom Kippur additional prohibitions are observed similar to the fast of Tisha B'Av, as detailed in the Jewish oral tradition (Mishnah tractate Yoma 8:1) because the Torah Leviticus 23:27 stipulates that ועניתם את נפשתיכם "and you shall afflict your souls" and the Talmud therefore defines self-imposed "affliction" during Yom Kippur only, as follows:
making the culmination of the ten days a very serious set of observances.
Yom Kippur is over at sundown on the tenth day at nightfall but is 'confirmed' as concluded after the recitation of the Kaddish following the end of ne'ila ("closing") prayer and the shofar is sounded. The services end in joy with the hope that all have been inscribed in the Book of Life.
As detailed in the Jewish Encyclopedia: