Description Rosh Hashanah, the Jewish New Year, is the first of the Jewish Holy High Days and one of Judaism.s holiest days. Often called the birthday of the world, it is celebrated on the first day of Tishrei, the seventh month of the Hebrew calendar. People celebrate this happy holiday with family and friends by praying, lighting candles, and eating special meals and sweet treats. Learn more about the history behind this important day and how it's observed today.