Hoshana Raba, is the 21st day of the month of Tishrei. It is also the seventh day of Succot, the festival's last day - well, not exactly. Although it is the final day of Hol Hamoed - the intermediate days of Succot - Hoshana Raba is followed by another day of the festival, Simhat Torah.
The Torah emphasizes the joy of this holiday, for after a harvest season of labor, we celebrate our prosperity.

Marc Israel Sellem/The Jerusalem Post

Hoshana Raba, is the 21st day of the month of Tishrei, and the final day of Hol Hamoed.

Marc Israel Sellem/The Jerusalem Post

The last day of Succot includes seven circles around the altar and special prayers, and was dubbed Hoshana Raba, "The Great Supplication."

Marc Israel Sellem/The Jerusalem Post

The Torah emphasizes the joy of this holiday, for after a harvest season of labor, we celebrate our prosperity.

Marc Israel Sellem/The Jerusalem Post

One ritual practiced in the Temple involved bringing large branches of willow and leaning them against the altar in the courtyard of the Temple.

Marc Israel Sellem/The Jerusalem Post

Throughout the ceremony, worshipers pray for merciful rains by reciting, "We beseech you, God, save us [hoshana]," from which the ritual derived its name.