Rosh Hashanah is the Jewish New Year. Many Jews celebrate by worshiping in a synagogue and reading passages from the Torah during religious services. The shofar (a hollowed-out ram's horn) is blown like a trumpet as a symbol of awakening listeners to the coming judgment, because ten days after Rosh Hashanah the holiday of Yom Kippur arrives, where God's books of humanity's righteousness are considered written and closed for the year.
Jews also celebrate the New Year with friends and loved ones by enjoying feasts of traditional food, including slices of apples and pieces of challah bread dipped in honey for a "sweet" upcoming year. This year, the holiday began at sundown on Sunday, October 2 and will continue through Tuesday evening.
If you'd like to wish someone a happy new year, you can use the greeting "Shanah tovah!", which means “Good year."