Rosh Hashanah (literally Head of the Year in Hebrew) is the High Holiday commonly known as the Jewish New Year. It is not a day to be spent in revelry, but in pious reflection. Rosh Hashanah marks the beginning of the civil year on the Hebrew calendar.
Rosh Hashanah is a day of rest, and activities normally prohibited on the Sabbath are also prohibited on Rosh Hashanah.