Trick-or-treating is a custom for children on Halloween. Children proceed in costume from house to house, asking for treats such as candy, or sometimes money, with the question, "trick or treat?" The "trick" is a (usually idle) threat to perform mischief on the homeowners or their property if no treat is given.
In the United States and Canada, trick-or-treating is now one of the main traditions of Halloween and it has become socially expected that if one lives in a neighborhood with children one should purchase treats in preparation for trick-or-treaters.
The tradition of going from door to door receiving food already existed in Britain and Ireland, in the form of souling, where children and poor people would sing and say prayers for the dead in return for cakes. Guising — children disguised in costumes going from door to door for food and coins — also predates trick or treat, and was traditional at Halloween in late 19th century Scotland and Ireland. While going from door to door has remained popular among Scots and Irish, the North American custom of saying "trick or treat" has recently become common. The activity is prevalent in the United States, United Kingdom, Canada, Ireland, Puerto Rico, and northwestern and central Mexico.
Sections of the pumpkin are cut out to make a hole often depicting a face, usually menacing like a demon or devil. A variety of tools may be used to carve and hollow out the gourd, ranging from simple knives and spoons to specialized instruments, typically sold in holiday sections of grocery stores. Printed stencils can be used as a guide for increasingly complex designs. After carving, a light source (traditionally a candle) is placed inside the pumpkin and the top is put back into place. The light illuminates the design from the inside. Sometimes a chimney is carved in. It is possible to create surprisingly artistic designs, be they simple or intricate in nature. But towards the end of the 20th century, artists began expressing every kind of idea they could imagine on pumpkins. Today, it is common to see portraits of political candidates, celebrities and cartoon characters. Pumpkin painting is also common, especially for children whose parents don't want them handling the sharp tools involved in carving.
The tradition of carving a lantern started in Ireland. However it was traditionally carved from a swede or a turnip. They were carved on All Hallows' Eve and left on the door step to ward off evil spirits. An offering or, as we now know it, a "treat" would also be commonly left, as it was feared if you didn't the demons and spirits would fiddle with property or live stock (play a "trick"). Once the tradition moved to the USA it was adapted to the carving of a pumpkin as these were more readily available and easier to carve. The ritual of "trick or treating" was soon invented to re-create the coming of demons and ghouls on the night to dwellings requesting a treat (which is now traditionally given as candy) or a trick would be played. The demons and ghouls are now of course children dressed up to represent them.