Yes, fasting on Yom Kippur is a central and traditional observance. It is a mitzvah (commandment) in the Torah to fast on Yom Kippur, the 10th day of the Jewish month of Tishrei, abstaining from all food and drink from before sundown on the eve of Yom Kippur until nightfall the next day. This fast lasts about 25 hours and is considered a way to afflict the soul, focusing on spiritual purification, prayer, and repentance.
Typically, males over 13 and females over 12 are expected to fast. Children under 9 do not fast, and those aged 9 to the age of religious maturity gradually learn to fast. There are exemptions for people with health risks, pregnant or nursing women, and those for whom fasting would be dangerous; in these cases, it is even considered a mitzvah to break the fast to preserve health.
The fast involves complete abstinence from food and drink, including water. It is customary to prepare for the fast by eating nourishing meals beforehand and staying hydrated. During the fast, prayer and synagogue services occupy much of the day.
In summary, fasting on Yom Kippur is customary and expected unless health reasons prevent it, in which case accommodations should be made.
