Checkout these funny Halloween pictures - Halloween is an observance celebrated on the night of October 31, most notably by children dressing in costumes and going door-to-door collecting sweets. It is celebrated in much of the Western world, though most common in Canada, the United States and England. Halloween originated among the Celts in Ireland, Britain and France as the Pagan Celtic harvest festival, Samhain. The term Halloween is shortened from All-hallow-even, as it is the evening before All Hallows Day (also known as All Saints Day). Halloween was also sometimes called All Saints Eve. Halloween is also called Pooky Night in some parts of Ireland, presumably named after the puca, a mischievous spirit.