Halloween (a shortening of All Hallows’ Evening),^[5] also known as Hallowe'en or All Hallows' Eve,^[6] is a yearly holiday observed around the world on October 31, the night before All Saints' Day. Much like Day of the Dead celebrations, the Christian feast of All Hallows' Eve, according to some scholars, incorporates traditions from pagan harvest festivals and festivals honouring the dead, particularly the Celtic Samhain;^[6][7][8] other scholars maintain that the feast originated entirely independently of Samhain.^[9] Typical festive Halloween activities include trick-or-treating (also known as "guising"), attending costume parties, carving jack-o'-lanterns, lighting bonfires, apple bobbing, visiting haunted attractions, playing pranks, telling scary stories, watching horror films, as well as the religious observances of praying, fasting and attending vigils or church services.^[3][2][4][1]

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.^[10] Although the phrase All Hallows' is found in Old English (ealra hālgena mæssedæg, mass-day of all saints), All-Hallows-Even is itself not attested until 1556.^[10]