Halloween, or Hallowe'en (/ˌhæləˈwiːn, -oʊˈiːn, ˌhɑːl-/; a contraction of All Hallows’ Evening), also known as Allhalloween, All Hallows' Eve, or All Saints' Eve, is a celebration observed in a number of countries on 31 October, the eve of the Western Christian feast of All Hallows' Day. It begins the three-day observance of Allhallowtide, the time in the liturgical year dedicated to remembering the dead, including saints (hallows), martyrs, and all the faithful departed.
According to BBC Online, it is "widely believed" that many Halloween traditions originated from the ancient Celtic harvest festival Samhain, and that this Gaelic observance was Christianized by the early Church. Samhain and other such festivals may have also had pagan roots. Some, however, support the view that Halloween began independently of Samhain and has solely Christian roots.
Halloween activities include trick-or-treating (or the related guising), attending Halloween costume parties, decorating, carving pumpkins into jack-o'-lanterns, lighting bonfires, apple bobbing and divination games, playing pranks, visiting haunted attractions, telling scary stories and watching horror films. In many parts of the world, the Christian religious observances of All Hallows' Eve, including attending church services and lighting candles on the graves of the dead, remain popular, although elsewhere it is a more commercial and secular celebration. Some Christians historically abstained from meat on All Hallows' Eve, a tradition reflected in the eating of certain foods on this vigil day, including apples, colcannon, potato pancakes and soul cakes.(Wikipedia)