This festival celebrates the Jews being freed from Egypt, and is a commemoration of the following 40 years which they spent in the desert before reaching the promised land. During this time they had to live in temporary shelters, and sukkot is the Hebrew word meaning temporary shelters. It’s a joint thanksgiving / harvest festival as they remember God feeding the Jews while they were in the desert.
For the festival, Jewish people live in a sukkah (singular of sukkot) for seven days. Usually they just have their meals in the sukkah, but some people choose to sleep in them as well. Guests are invited to dine in the sukkah and Abraham and Sarah are thought of amongst the guests.
Although the festival is fun, there are some rules for building a sukkah: it must have at least three walls, it must be made from natural materials such as wood or stone – definitely no plastic (!) , and you must be able to see at least three stars through the roof.