Samhain, pronounced "sow-en", is the Witches' New Year and one of the four Greater Sabbats of Witchcraft. Samhain is considered as a time to celebrate the lives of those who have passed on, and it often involves paying respect to ancestors, family members, elders of the faith, friends, pets, and other loved ones who have died. In some rituals, the spirits of the departed are invited to attend the festivities. It is seen as a festival of darkness, which is balanced at the opposite point of the wheel by the festival of Beltane, which is celebrated as a festival of light and fertility.
At Samhain, the veil between this world and the Otherworld is at its thinnest point of the whole year, making it easier to communicate with those who have left this world. The veil between the worlds begins to thin around mid-October, reaches it's peak between October 31 and November 7, and typically returns to normal around November 10, depending on which date the actual astrological cross-quarter day falls (which varies from year to year).