The Literal Commandment
You shall live in booths for seven days; all the native-born in Israel shall live in booths, so that your generations may know that I had the sons of Israel live in booths when I brought them out from the land of Egypt. I am the LORD your God. (Leviticus 23:42-43)
The literal commandment is that we should live in "booths" (temporary structure) for seven days during Sukkot: the Feast of Tabernacles.