Sukkot is the last of the three pilgrimage festivals. Like Passover, and Shavuot, Sukkot has a dual significance: historical and agricultural. Historically, Sukkot commemorates the forty-year period during which the children of Israel were wandering in the desert, living in temporary shelters.
Sukkot lasts for seven days. The two days following the festival, Shemini Atzeret and Simchat Torah, are separate holidays but are related to Sukkot and are commonly thought of as part of Sukkot. On Shemini Atzeret we begin to pray for rain and also commemorate those who have died in the past year with Yizkor services. Simchat Torah is the holiday where we begin reading the Torah anew.