Halloween began as the ancient Celtic New Year, known as Samhain, thousands of years ago. The holiday fell on the first of November, and marked the end to the revered "season of the sun." It was during this time that the ancient Celts believed that the veil between the spirit world and the mortal world was thinnest, and therefore performed rituals to honor the dead, keep evil spirits at bay, and to ensure that the sun could come back in the spring.
On the eve of Samhain, October 31st, Celtic villagers would extinguish the fires in their hearths, and all would meet near the local oak forest. The Celtic priests, known as druids, would lead ritual ceremonies and create bonfires. Animal sacrifices were then offered to the gods and those who had died within the past year, and the villagers would dance in the skins and furs of dead animals. After the festivities, a coal from the bonfire would be given to each family to light their hearths with, because it was believed that these coals would provide a family with good luck in the New Year, would ensure a bountiful harvest in the year to come, and would keep away evil spirits.
Years after the Romans had invaded much of the Celtic lands, from Gaul to Britain, the Samhain tradition was mixed with the Roman holiday, Pomona Day. Pomona Day honored the goddess Pomona, and celebrated the fruits of the harvest. It was from this holiday that the tradition of bobbing for apples began.
The mixed holiday of Samhain and Pomona Day soon competed with the Christian faith. The Roman Catholic Church deeply resented the traditions of the "pagans" and "savages," and sought to erase all the rituals of the Celtic and Roman harvest seasons. They began to portray the druid priestesses as evil witches that embodied everything unholy, and, supposedly, everything feminine. But the pagans stayed firmly rooted in their beliefs, and soon prompted the Church to create All Saint's Day on November 1, to honor, of course, the saints of the Catholic faith.