Sukkot, the Jewish festival of booths (a harvest holiday of thanksgiving), begins on the 15th day of the Hebrew month of and lasts for seven days. The first day of Sukkot is a festival day; the second through seventh days are known as of Sukkot. The day after Sukkot ends is Sh’mini Atzeret (literally, the assembly of the eighth day), on which Simchat Torah (the Festival of rejoicing in the Torah) also is observed. This day, too, is a festival day.
Adapted from: Jewish Living: A Guide to Contemporary Reform Practice