The first group is the Four Greater Sabbats, or the Fire Festivals, and the second is the Lesser Sabbats, or Cross Quarter Sabbats.
Samhain is celebrated sometime between October 31st and November 11th. It is also known as the Witch's New Year and it is said that the veils between the living and the dead wane thin. .
Imbolgc, also known as Candlemas, is celebrated on February 2nd. The Goddess is honored for giving birth of the Lord on this day. Candles are lit and are let to burn all day in order to draw the sun to people for it is also the first day of the Wiccan Spring. .
Third is Beltaine which falls on April 30th or May 1st. This is the celebration of rebirth as it falls directly opposite of Samhain. The East is the quarter celebrated here and this holiday is where the maypole is used. It is also the holiday of love and romance. .
The fourth Fire Festival is Lammas. Also known as the Wedding Feast or the First Feast of Harvest, this day is celebrated on August 1st. Spirit is given thanks to for the abundance of earth and represents the Wiccan Thanksgiving.
The first Lesser Sabbat is the Winter Solstice, or Yule. It is celebrated on the winter solstice--typically December 21st or 22nd. This is where the Christian Christmas derived from as well as the images of Father Christmas or Santa Claus. The Wiccan Father Christmas is the Holly King who is said to have defeated the Oak King in a battle at this time. The Holly King is what you would expect Santa Claus to look like and he drives a sleigh of eight deer representing the eight Sabbats and the horned God.
Next comes the Spring Equinox, also known as Ostara. The original tradition of coloring eggs was that of the Witches to celebrate Ostara to represent the return of fertility to the land. They also right their Karmic wrongs at this time and bring balance to themselves.
The Summer Solstice is when God is celebrated in all of his passion and glory.