Hoshana Rabbah

Hoshana Rabbah (Hebrew: הוֹשַׁעְנָא רַבָּא) is the seventh day of Sukkot. During the six days of Sukkot, a Torah scroll is removed from the Ark and brought to the bimah. The Chazan and congregation say the first four Hoshanot responsively.

They then circle the bimah holding the Lulav and Etrog and recite the longer Hoshana prayer for the respective day Sukkot. Each Hoshana is done in honor of a patriarch: Abraham, Isaac, Jacob, Moses, Aaron, Joseph and David.

these prayers for redemption are also known as Hoshanot because each stanza of the prayer is accompanied by the word Hoshana.

During the first six days of the Festival, the Chazan circles the bimah once. On Hoshana Rabbah, the seventh and the last day of the Festival of Sukkot, seven circles are made. Hoshana Rabbah is known as the last of the Days of Judgment which began on Rosh Hashana.

Many Jews choose to stay awake all night on Hoshana Rabbah and recite the Tikkun service, read from the Book of Deuteronomy and recite the entire Book of Psalms.
According to the Zohar, although the judgment for the new year is sealed on Yom Kippur, one can still change his ways and regret his sins until the end of Sukkot.

Credit:
Chabad