History of Halloween

The word Halloween is first attested in the 16th century and represents a Scottish variant of the fuller All-Hallows-Even (“evening”), that is, the night before All Hallows Day

Carving of jack-o’-lanterns springs from the souling custom of carving turnips into lanterns as a way of remembering the souls held in purgatory

The practice of dressing up in costumes and begging door to door for treats on holidays dates back to the Middle Ages and includes Christmas wassailing. Trick-or-treating resembles the late medieval practice of souling, when poor folk would go door to door on Hallowmas, receiving food in return for prayers for the dead on All Souls’ Day .

The practice of dressing up in costumes and begging door to door for treats on holidays dates back to the Middle Ages and includes Christmas wassailing. Trick-or-treating resembles the late medieval practice of souling, when poor folk would go door to door on Hallowmas , receiving food in return for prayers for the dead on All Souls’ Day.

Excerpts from Wikipedia
http://en.wikipedia.org/wiki/Halloween