When and why is Rosh Hashanah celebrated?

Rosh Hashanah is the first two days of the month of Tishrei, and is the Jewish New Year. Our traditions state that at that time the world is judged for the coming year (Talmud, Rosh Hashanah 16a); and we read the Torah and say prayers which ask for a good year and which declare God's kingship over the world. The shofar (ram's horn) is blown (Leviticus 23:24; Talmud, Rosh Hashanah 33b-34a), symbolically heralding God's kingship, and calling to mind the covenant of Isaac (see Genesis ch.22). Festive meals are held in the home, and traditional foods (such as the well-known Apple dipped in honey) are eaten to symbolize a sweet year.