Sukkot

Sukkot is an 8 day Biblical pilgrimage festival, it is also known as The Feast of Booths (Tabernacles). The first two days are celebrated as full holidays. The following five days are known as Hol Hamo'ed - weekdays that retain some aspects of the festival. The seventh day (fifth of the intermediate days) is Hoshanah Rabbah - and has a special observance of its own. The last day, the eighth, is celebrated as separate holiday, with its own special prayers and customs (see below). Erev Sukkot, the first night of the holiday, is on Tishri 14, so the first day of Sukkot is on Tishri 15.

Sukkot commemorates the life of the Israelites in the desert during their journey to the promised land. During their wandering in the desert they lived in booths (Sukkot). The Torah directs Jews to use four species of plants to celebrate the holiday: The lulav (palm branch), etrog (lemon-like citron), myrtle, and willow. The etrog is handled separately, while the other three species are bound together, and are collectively referred to as the lulav.

Hosha'nah Rabbah - The seventh day of Sukkot.

Shemini Atzeret - The eighth day of Sukkot.

Simhat Torah - The finale of Sukkot.

In Israel, Sukkot is eight days long, including Shemini Atzeret. Outside Israel (the Diaspora), Sukkot is nine days long. Thus the eighth day is Shemini Atzeret, and the extra (ninth) day is Simchat Torah. In Israel, the festivities and customs associated with Simchat Torah are celebrated on Shemini Atzeret.

The last portion of the Torah is read on this day. The following Shabbat we start the Torah again at the beginning of Bereshis (Genesis). Services are unconventionally joyous, and humorous deviations from the standard service are allowed, and even expected.