Sukkot, also known as Feast of Booths or Feast of Tabernacles, is a biblical holiday which is celebrated from September 21, 2021 to September 27, 2021. Sukkot is the 15th day of the month of Tishrei, the first month of the Jewish calendar (variously from late September to late October). It is one of the three biblically mandated festivals Shalosh regalim on which Hebrews were commanded to make a pilgrimage to the Temple in Jerusalem. It follows the solemn holiday of Yom Kippur, or the Day of Atonement.
The holiday lasts seven days (eight in the diaspora). The first day (and second in the diaspora) is a sabbath-like yom tov when work is forbidden, followed by the intermediate Chol Hamoed and Shemini Atzeret. The Hebrew word sukkōt is the plural of sukkah, "booth or tabernacle", which is a walled structure covered with skhakh (plant material). Throughout the holiday, meals are eaten inside the sukkah and some people sleep there as well. On each day of the holiday, members of the household recite a blessing over the lulav and etrog.
The second through seventh days of Sukkot (third through seventh days outside Israel) are called Chol HaMoed. These days are considered by halakha to be more than regular weekdays but less than festival days. In practice, this means that all activities that are needed for the holiday – such as buying and preparing food or cleaning the house in honor of the holiday – are permitted by Jewish law. Activities that will interfere with relaxation and enjoyment of the holiday – such as laundering, mending clothes, engaging in labor-intensive activities – are not permitted. (With material from: Wikipedia)