Rosh Hashanah, the Jewish New Year, is observed on the first day of the month of Tishrei on the Hebrew calendar, which falls in September or October on the Gregorian calendar (the calendar in common use throughout the world). It is a holy day marked by intense moral and spiritual introspection.
There are a number of beautiful customs associated with Rosh Hashanah. People greet each other with the words, "le-shanah tovah tikatevu v'taychataymu," meaning, "May you be inscribed and sealed for a good year."
This practice stems from the traditional imagery in which God sits in judgment during the Ten Days of Repentance (the ten days between Rosh Hashanah and Yom Kippur, the Day of Atonement), deciding the fate of every living thing.
On Rosh Hashanah, Jewish tradition tells us that God opens up three books — one for those who were righteous during the year, one for those who were wicked, and one for those whose good and bad deeds balanced. Everyone's fate is inscribed in one of those three books.
During the Ten Days of Repentance, however, Jews believe they can alter the course of their destiny by repenting, praying, and doing acts of charity. On Yom Kippur, the final day of judgment, God closes all three books and seals humankind's verdict for the coming year.