Rosh Hashanah (New Year) also known as Yom Terua (the Day of emitting loud sounds)
ראׁשׁ הַשָּׁנָה אוֹ יוֹם תְּרוּעָה
The New Year begins on the 1st day of the month of Tishri, the worship assembly is on this day. This day is also called Yom Terua.
During this day the joyful cries announce to each Israelite the upcoming joyous events.
The ten days from the beginning of the month till the festival of Yom Kippur we call the Ten days of repentance.
During these ten days we wake up in the night before sunrise and we read the prayers of repentance - סְלִיחוֹת selikhot - specially compiled for this repentance.