The origin of Halloween is a far cry from modern tradition's vampires, trick-or-treating and candy corn. Dating back about 2,000 years, Halloween was originally called Samhain, and marked the beginning of the Celtic New Year.

Roughly translated from Irish Gaelic, Samhain means "summer's end," according to "Creating Circles & Ceremonies: Rituals for All Seasons And Reasons" (Career Press, 2006). In ancient times, the holiday marked the transition from the "light" part of the year to the "dark" portion, as daylight hours became shorter and the weather grew colder. For this reason, the holiday is also known as "harvest's end" and "winter's beginning."

The day was celebrated starting at sundown on October 31 and through the day on November 1. It was believed — and is still believed by Pagans and Wiccans — that Samhain is when the veil between this world and the spirit world is thinnest, and departed spirits can return to mingle with the living.

"In the European traditions, Samhain is the night when the old God dies, and the Crone Goddess mourns him deeply for the next six weeks," according to "The Sabbats: A New Approach to Living the Old Ways" (Llewellyn Worldwide, 1994). "The popular image of her as the old Halloween hag menacingly stirring her cauldron comes from the Celtic belief that all dead souls return to her cauldron of life, death and rebirth to await reincarnation."

All Saints Day began to take the place of the Celtic Samhain holiday when the Christian Church began to spread throughout Ireland, around 700 A.D., according to "Ireland" (Random House, Inc., 2007). The night before All Saints Day, October 31, came to be called All-Hallows Eve, Hallowmas, or Hallowe'en, according to "Creating Circles & Ceremonies."

"Like many other pagan festivals, the Christians adapted Samhain and made it a Christian event," said Joan HanniganVogt, a spokesperson for the Tara Circle, an Irish cultural organization in Yonkers, N.Y. "The Celtic people used to celebrate the event by wearing costumes, which represented various Celtic deities."

The ancient Celtics also lit bonfires to guide the souls of the deceased to "the other side," played funeral games and kept hearths burning all night for protection from evil spirits. The custom of handing out candy on Halloween stems from the Celtic tradition of giving food and money to costumed celebrants, just in case they were the physical incarnations of lost souls.

"The modern trick or treat is obviously a mimic of the custom of doing things to please the spirits or risk some evil," HanniganVogt told Life's Little Mysteries.

The jack-o'-lantern, a Halloween staple, also has its roots deep in Celtic soil. Based on a folklore tale about a forlorn ghost named Jack, jack-o'-lanterns were originally made using a hollowed-out turnip with a small candle inside, and were set out during Samhain to guide lost souls — and scare away evil ones.

When the Irish potato famine of 1846 forced Irish families to flee to North America, the jack-o'-lantern came with them. But turnips were hard to come by in the states, and pumpkins proved to be the perfect substitute, according to "Halloween and Commemorations of the Dead" (Infobase Publishing, 2009). Americans embraced Irish Halloween festivities, and the jack-o'-lantern tradition carries on to this day.

This article was provided by Life's Little Mysteries, a sister site to LiveScience.