What is Samhain?
Samhain (typically pronounced SAH-win or SAH-wen) occurs on October 31. Ancient Celts celebrated this day as the beginning of the new year. The word itself is rooted, of course, in Gaelic and literally means "summer's end."
The Celts considered the beginning of the year as a time to reflect upon those who had lost their lives in the preceding year. Additionally, the New Year was viewed as a time to shed losses. Accordingly, a great feast took place on Samhain to commemorate the dead, for which the portions of the animal flocks least likely to survive through winter were typically slaughtered and consumed.
Celts also conventionally believed that the division between the worlds of the living and the dead was at its thinnest around Samhain. Among other traditions, it was common for Celts of yore to leave a plate of food outside after the feast for consumption by one's ancestors or any other souls who might drop by that evening.
While no such ritual sacrifices occur in the present day, Wiccans and many other neopagans celebrate Samhain as a high festival (also called a Sabbat). Commemorative rituals are often performed, and many pagans take advantage of the proximity to the land of the dead to perform divination and other means of spiritual contact.
For further information, please visit the following links regarding Samhain:
The Witches' Voice: A Quick Intro to Samhain