Pronounced Sow-in, this Sabbat falls on October 31st. Yes, inded, it is Halloween. But let'ds go into the Wiccan reasons and celebrations of Samhain and go a few paces away from how Halloween is traditionally celebrated in the United States.
Samhain is traditionally the time when the viel between worlds are the thinnest. THe viel becomes thin at other times of the year, such as the Equinoxes, but it's believed that it is thinnest at Samhain. Looking back on how Wiccans look at death and the afterlife we see the belief in reincarnation with perhaps a period of rest inbetween lives in a peaceful, restful place. This peaceful place is sometimes called the Summerlands, one of the other worlds the viel seperates from our own. So, Samhain is an excellent time to contact or invite back the spirits of loved ones from the Summerlands. This practice makes Samhain a type of Memorial Day, when we remember and maybe touch on the spirit of our loved ones.
Another aspect of Samhain is the agracultural aspect. It is a harvest, the last harvest of the year. Apples and nuts are the traditional foods gathered at this time. Apple cider is sometimes used during the feast to reflect this. So, Samhain is also the Thanksgiving Day of the Wicans. As they remember their dead, so to do they give thanks for what they have recieved during the year.
One more aspect of Samhain is that it was the Celtic New Year. I've even sen fireworks set of at public rituals to signify this part of Samhain.
To bring all these aspects together, within the framework of the typical Samhain ritual one would find the inviting in of the dead or ancestors, with a rememberance of those who have passed on during the previous year. This looking back also includes looking back at all one's accomplishments, and a thanksgiving is ofered. Then there is a looking ahead, as resolutions are given for gaols in the year ahead. A common theme of Sabbats is banishing of the old (maybe bad habits or traits) and the taking on the next years goals. The banishing part being emphasized during the harvesting times of the year, while goals are emphasized during planting seasons.
ONe note of the communing with the dearly departed is that it is a celebration, not necromancy, in the Hollywood sence. MOvies and T.V. has shown rituals where the dead are raised and asked to perform the bidding of the summoner... that's television. The Samhain ritual is to gather together loved ones to party once more. Sometimes a "dumb supper" is left out for the dead, to show them that even though they have traveled on, they are remembered and still seen as part of the family.