Halloween also known as All Hallows Eve is celebrated on the eve of All Saints Day throughout the western world on October 31st to commemorate the remembering the dead, including saints (hallows) martyrs, and all the faithful departed believers. The word Halloween dates back to 1745.
It is thought to have come from a Scottish term for All Hallows' Eve meaning Holy Evening. This day marked the end of summer and the harvest and the beginning of the dark, cold winter, a time of year that was often associated with human death.
In ancient times, a feast influenced by western European harvest festivals, and festivals of the dead with possible pagan roots, particularly the Celtic Samhain, Lord of the Dead was arranged on this night. The customs that are abided by today are also thought to have been influenced by the folk customs and beliefs of the Celtic-speaking people and are rooted in paganism.
Trick-or-treating is a customary celebration for children on Halloween who go in costume from house to house, asking for treats such as candy or sometimes money. The word "trick" refers to "threat" to perform mischief on the homeowners or their property if no treat is given.