Sukkot is the Festival of the Booths in Judaism. It's a long tradition that began in Israel when the Jews would build little huts near the edges of their fields in the harvest season. It celebrates the harvest and comes a mere four days after Yom Kippur, the day of atonement. These photos of a sukkah were taken at Congregation Or Shalom in Orange.
Lulav and Etrog (above and below)
"On the first day you shall take the product of hadar trees, branches of palm trees, boughs of leafy trees, and willows of the brook, and you shall rejoice before Adonai your God seven days." "The first day" refers to the first day of Sukkot.
The four are lumped together under the inclusive term lulav, since the lulav is the largest and most prominent. Thus, while the mitzvah is to wave the lulav, this actually refers to the four taken together as one.
"Fruit of goodly trees" refers to the etrog (citron). "Branches of palm trees" refers to the lulav. "Boughs of leafy trees" refers to the myrtle (hadasim). "Willows of the brook" refers to the aravot or hoshanot.*
Covering the Challah
*From My Jewish Learning website