Yom Kippur, the Day of Atonement, is the holiest day on the Jewish calendar. Occurring on the 10th day off the Hebrew month Tishrei, Yom Kippur is the final day for Jews to seek forgiveness of sins committed against people and God from the past year, and to be inscribed in the Book of Life for another year. The most important part of the day is the fast, a 25-hour period in which no food or drink is consumed.
The Night Before
Eat a healthy dinner. Don't overeat, but it's OK to feel full.
Avoid alcohol, caffeine, overly salty foods or overly sweet foods that might cause thirst.
Get a good night of sleep.
On Yom Kippur
When you wake up, remind yourself to move slowly throughout the day. You don't want to exert any extra energy.
Wear comfortable clothing that is appropriate for both synagogue and the weather outside.
Attend synagogue. There are services all day, and it's the best place to be because you're surrounded by other fasting people. Focus on the prayers, not your stomach or throat.
Take a nap. It's the best way to quickly pass time. You can take one either at home or during a break in the services at synagogue.
If you don't stay for services all day (and many leave after the morning service, which usually lasts into early afternoon), busy yourself with quiet activities, such as reading or watching TV.