The day of atonement that's Yom Kippur in a nutshell. It follows the Jewish new year Rosh Hashanah http://www.gather.com/viewArticle.action?articleId=281474980459398
9 days later. It's the holiday where you try your very best to atone for your sins that you did all year. It also happens to be a fast day of 25 hours! Before the fast and prayers begin you eat a special meal called Seudah Mafsekt it's basically the large meal meant to keep you full to an extent . You're meant to get hungry after a certain point.
This holiday is followed by Sukkot http://www.gather.com/viewArticle.action?articleId=281474977899860