Sukkos is a seven-day holiday that is biblically mandated. This holiday starts on the 15th of Tishrei and ends on the 21st of Tishrei, a day known as Hoshanah Rabbah. The following two days of Shmini Atzeres and Simchas Torah come immediately after Sukkos, on the 22nd and 23rd of Tishrei, but are a holiday unto themselves. Note that in Israel the two days of Shmini Atzeres and Simchas Torah are combined into one day.
We read, “In a Sukkah you shall dwell for seven days…” The Torah goes on to explain that by sitting in the Sukkah we remember how G-d settled the Jews in booths (Sukkahs) when they left Egypt. Hashem enveloped the Jewish nation in a protective cloud shelter, with a cloud above to keep them shaded, a cloud below to soften the desert terrain, and clouds on each side to keep them safe.
As such, Jews the world over erect booths out of wood, hard plastic, canvas, and other materials in the days leading up to Sukkos. These booths are covered over with Schach, which is the material that covers the Sukkah, usually made from large branches, twigs, or long bamboo sticks. Throughout the seven days of Sukkos the Jewish nation eats, sleeps, studies, and spends their free time in the temporary dwelling of the Sukkah.
The Torah also commands us to take the “Four Species” on Sukkos, which are the Esrog, Lulov, Hadasim and Aravos. Holding the Esrog in the left hand and the other three species in the right hand, we make a blessing and wave them in all six directions. Some have the custom to wave the Four Species in the Sukkah.