Trick-or-treating and guising

Trick-or-treating is a customary celebration for children on Halloween. Children go in costume from house to house, asking for treats such as candy (sweets) or sometimes money, with the question, "Trick or treat?" The word "trick" refers to a (mostly idle) "threat" to perform mischief on the homeowners or their property if no treat is given. In this custom the child performs some sort of trick, i.e. sings a song or tells a ghost story, to earn their treats. 

Around the world

The traditions and importance of Halloween vary greatly among countries that observe it. In Scotland and Ireland, traditional Halloween customs include children dressing up in costume going "guising", holding parties, while other practices in Ireland include lighting bonfires, and having firework displays.Mass transatlantic immigration in the 19th century popularized Halloween in North America, and celebration in the United States and Canada has had a significant impact on how the event is observed in other nations. This larger North American influence, particularly in iconic and commercial elements, has extended to places such as South America, Australia,New Zealand, (most) continental Europe, Japan, and other parts of East Asia.


Information from ：Wikipedia