Yom Kippur is the most sacred event in the Jewish calendar and is traditionally observed with a period of fasting and prayer.
When is it?
Known as the Jewish "Day of Atonement", it begins in 2017 on the evening of 29 September. It falls each year on the 10th day of the Jewish month of Tishrei, ten days after Rosh Hashanah, the Jewish New Year. Yom Kippur is a day to reflect on the past year and ask for forgiveness for any sins.
The period in between Rosh Hashanah and Yom Kippur is referred to as the "Days of Repentance" or "Days of Awe" – a time when Jews can make a commitment to not repeat wrongs made in the last year.
What happens on Yom Kippur?
The day of Yom Kippur is marked in a number of different ways. No food and drink is consumed for 25 hours, but children under 13 and people who are unwell or pregnant are not required to fast. Some wear white as a symbol of purity and many abstain from wearing make-up or perfume and bathing.
The Talmud – a central text of Judaism – specifies people cannot wash or anoint their bodies with cosmetics or deodorant. Some also abstain from sex.
Most importantly, Jews observing Yom Kippur will spend time in the synagogue, as it is the only day of the year with five services. Unlike a normal day, where there are three prayer services, there are five on Yom Kippur: Ma'ariv, Shacharit, Musaf, Mincha and Ne'ilah. Services include private and public confessions.
Ne'ilah is the concluding service of Yom Kippur. It normally lasts about an hour, during which the ark – where the scrolls of the Torah are kept – are left open throughout. This is considered the last chance to atone for sins before the end of the holiday and is sometimes referred to as the closing of the gates.
The day is spent in continuous prayer for forgiveness until the end of the day is marked with the sound of the shofar, a traditional instrument made from a ram's horn.
While not mandatory, it is considered good religious practice to make a charitable donation the day before Yom Kippur.
In some communities, the ritual of Kapparot takes place the night before Yom Kippur. A live chicken or bag of coins is swung by a person over their head three times, transferring their sins to the creature or object. The chicken is then slaughtered and donated to the poor for a meal ahead of the fast.