In the morning services of Hoshanna Rabbah, following Musaf (and some places after hallel) the hoshanot are said as written in the prayerbook, the congregation marches around the bima seven times, after which comes the beating of the aravah, willow branch. The aravahs are beaten against the floor five times. No blessing is recited over the beating of the aravah since it was merely a custom.
Hoshana Rabbah is known as the day of the final sealing of judgment, which began on Rosh Hashannah. During the festival of Sukkot the world is judged for water and for the blessings of the fruit and crops. The seventh day of the festival is the final sealing and since human life depends on water, Hoshanna Rabbah is somewhat similar to Yom Kippur. Hence there are additional prayers and quests for repentance as on Yom Kippur.