The Wiccan calendar is often referred to as the "Wheel of the Year", emphasizing the cyclical nature of the world around us. Each holiday has a wealth of history and tradition surrounding it, but this page should explain the basics of each Sabbat and how we celebrate.

Yule
Approx. Dec 21
Winter Solstice, Saturnalia, Alban Arthan
The holiday of Yule was celebrated long before Christians adopted the date. Many of the Christmas traditions we see today stem from old Pagan customs. As the solstice, it is the longest night of the year. From this day forward, light begins to return and we celebrate the rebirth of the Sun God.
Traditions: lighting the Yule log, wreath making, gift giving
Correspondences: pine, holly, myrrh, cinnamon,

Imbolc
Feb 2
Candlemas, Imbolg, Brigid's Day
Imbolc is a day to celebrate the first glimpses of Spring, and it is also dedicated to the Celtic Goddess Brigid. Non-Pagans celebrate today as Groundhog Day. Make new starts in life, as you give your home a thorough cleaning.
Traditions: Burning fires and candles, cleaning, making a bed for Brigid
Correspondences: carnation, rosemary, chamomile, milk

Ostara
Approx. March 21
Spring Equinox, Lady Day
This is another holiday that has been overlaid with Christian meanings (Easter). Eggs and bunnies are typical symbols, representing new birth and new life. Plant the seeds of long-term goals.
Traditions: Colouring eggs, decorating with flowers
Correspondences: jasmine, daffodil, lotus, new spring flowers

Beltane
May 1
May Day, Walpurgis Night
The God born at Yule is now a man, and the sacred marriage between God and Goddess is consumated. Beltane is a celebration of fertility, growth, love and passion. However you celebrate Beltane, do it with joy and happiness.
Traditions: Dancing around the May Pole, lighting bonfires
Correspondences: Rose, lilac, vanilla

Midsummer
Approx. June 21
Litha, Summer Solstice, Whitsun
Midsummer is the longest day of the year, and the strength of the Sun God begins to wane. The Goddess has left her Maiden form of Imbolc and is now in her Mother aspect. Refill your herb collection for the coming year.
Traditions: Fairy magick, collecting herbs
Correspondences: Orange, lemon, honeysuckle, vervain

Lammas
August 1
Lughnasadh,
As the first of the three harvest festivals, much of the symbolism for Lammas revolves around grains and bread. Sacrifices were common, though mostly symbolic, in order to ensure the continued success of the harvest.
Traditions: Bread baking, making corn dollies
Correspondences: corn, sandalwood, heather

Mabon
Approx. Sept 21
Autumn Equinox, Cornucopia
Day and night are equal again, and the weather grows colder as winter approaches. This is the second harvest festival. Rituals of thanks at this time have brought about the modern holidays of Thanksgiving. Take some time to think about what you are thankful for.
Traditions: Making and drinking of wine, share with the less fortunate
Correspondences: grapes, blackberries, cedar, patchouli

Samhain
Oct 31
Hallowe'en, All Hallows
Samhain (SOW-en) is the one Sabbat that is also widely celebrated amongst non-Pagans. The God has died, and the Goddess mourns him until his rebirth at Yule. It's the last harvest festival, and the end of the Wiccan year.
Traditions: Divination, honouring the dead, carving Jack o' Lanterns
Correspondences: pumpkins, apples, sage, mugwort

http://paganwiccan.about.com/library/basics/blsabbats.htm