The sabbats of the Witches are 8. Yule, Imbolc, Ostara, Beltane, Midsummer, Mabon, Samhain and Yule.

There are several names for each Sabbat and the date they fall on varies year to year. For example Ostara is also called Candlemas. Midsummer is also called Litha or Summer Solistice.

This is because Pagans' holidays follow the agricultural cycle. For example Samhain is the last harvest holyday.
Typically, in the Northern Hemisphere this is when the last crops are sown and gardens/fields are made ready for winter.
For example Ostara is March 20-22. It depends on the year.

Soon I will put information for each sabbat up. Now remember: each tradition has their own ways of doing things. What I will post is how I and my group do things. Think of this as a guide, not "the way it is done."