What are Hakafot?
On the night preceding Simchat Torah and again the following morning ["they could've danced all night!"], Jews all over the world (in Israel, Shmini Atzeret and Simchat Torah are rolled into one) dance joyously with the Torah.
Each dance is begun with a circuit of the bimah (the central platform in the synagogue from which the Torah is read), which symbolizes the altar in the Temple, by Jews carrying scrolls of the Torah taken from the Ark. This is done seven times, each to its own "lyrics," but all to a standard melody.
This is followed by exuberant dancing, to the sound of various Hebrew melodies, ranging from the ancient to the old to the new, a capello (without instrumental accompaniment).
The songs are based mainly on phrases from the Bible, or the Talmud, or Jewish tradition, and the dances continue for an undetermined length of time, or until they are stopped by the Rabbi, in the interest of allowing the congregants to get some sleep, or the Gabbai (Sexton) - an officer of the shul responsible for ritual matters, or until the dancers become exhausted, whichever comes first.