According to the Old Testament, the House of Israel was supposed to observe 3 annual feasts: Pesach (Passover), Shavuot (Weeks), and Sukkot (Tabernacles). Each Feast was an occasion for Israel to renew their devotion to God. Also, each of the Feasts looks back as a reminder of God's deliverance as well as looks forward as a type and shadow of glorious future events.
Passover commemorated the passing over of the angel of death which look the life of all the firstborn in Egypt. Passover as a type, prefigured the atonement, crucifixion and death of the holy Messiah. Shavuot commemorates the giving of the Law to Moses after being delivered from bondage. Also, Shavuot or Pentecost prefigured the giving of the Gift of the Holy Ghost following Christ's assention. Finally, Sukkot commemorates Israel dwelling in tents after leaving Egypt. Also, Sukkot is a type and shaddow of a great gathering of the righteous at Adam-ondi-ahman in the Last Days before the second coming of Jesus Christ.
Sukkot has great symbolism associated with it. The Feast of Tabernacles or Ingathering is celebrated right after the fall harvest each year. I'm sure it would be easy for anyone to feel very wealthy at harvest time. However, it is just at this precise time when God calls for His people to leave their homes and joyfully dwell in tents or booths with their families for 8 days. This commandment serves to remind us that happiness does not come from our material possessions but from our families and our relationship with God.
Israel was also to pay their tithes and offereings during this time. Israel was specifically instructed to remember the fatherless the the widow. Concern for the poor and the stranger were major parts of all the feast observances.
In addition to being commanded to be a "happy camper", Israel was commanded to decorate using citrus fruit, and branches from the willow, myrtle, and palm trees. The arrangement of the "4 kinds (species), is a reminder of the importance of unity. While we all should aspire to have the pleasant fragrance (faith), and sweet taste (works) of the citrus fruit, every person is important to God.
Today, God's people participate in a weekly Lord's Supper and pay tithes and offerings on a monthly basis instead of just 3 times a year. But just in case you may think we are off the hook from observing the Lord's Feast's, Zechariah prophesies that in the Last Days after Armageddon, all nations who attacked Israel will be required to observe Sukkot.
And it shall come to pass, that every one that is left of all the nations which came against Jerusalem shall even go up from year to year to worship the King, the Lord of hosts, and to keep the feast of tabernacles. (Old Testament, Zechariah, Zechariah 14:16)