Trick-or-treating , is an activity for children on or around Halloween in which they proceed from house to house in costumes, asking for treats such as confectionery with the question, "Trick or treat?" The "trick" part of "trick or treat" is a threat to play a trick on the homeowner or his property if no treat is given.

Trick-or-treating is one of the main traditions of Halloween. 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 National Confectioners Association reported in 2005 that 80 percent of adults in the United States planned to give out confectionery to trick-or-treaters, and that 93 percent of children planned to go trick-or-treating .

The activity is popular in the United States, the United Kingdom, Ireland, Canada, and due to increased American cultural influence in recent years, imported through exposure to US television and other media, trick-or-treating has started to occur among children in many parts of Europe, and in the Saudi Aramco camps of Dhahran, Akaria compounds and Ras Tanura in Saudi Arabia.

The most significant growth — and resistance — is in the United Kingdom , where the police have threatened to prosecute parents who allow their children to carry out the "trick" element. In continental Europe, where the commerce-driven importation of Halloween is seen with more skepticism, numerous destructive or illegal "tricks" and police warnings have further raised suspicion about this game and Halloween in general.

In Sweden children dress up as witches and go trick-or-treating on Maundy Thursday (the Thursday before Easter) while Danish children dress up in various attires and go trick-or-treating on Fastelavn (or the next day, Shrove Monday).

In Ohio, Iowa, and Massachusetts, the night designated for Trick-or-treating is often referred to as Beggars Night .

The practice of dressing up in costumes and begging door to door for treats on holidays goes back to the Middle Ages, and includes Christmas wassailing. Trick-or-treating resembles the late medieval practice of "souling," when poor folk would go door to door on Hallowmas (November 1), receiving food in return for prayers for the dead on All Souls Day (November 2).

It originated in Ireland and Britain, although similar practices for the souls of the dead were found as far south as Italy. Shakespeare mentions the practice in his comedy The Two Gentlemen of Verona (1593), when Speed accuses his master of "puling [whimpering, whining], like a beggar at Hallowmas."

Yet there is no evidence that souling was ever practiced in America , and trick-or-treating may have developed in America independent of any Irish or British antecedent. There is little primary documentation of masking or costuming on Halloween — in Ireland, the UK, or America — before 1900.

The earliest known reference to ritual begging on Halloween in English speaking North America occurs in 1911, when a newspaper in Kingston, Ontario, near the border of upstate New York, reported that it was normal for the smaller children to go street guising (see below) on Halloween between 6 and 7 p.m., visiting shops and neighbors to be rewarded with nuts and candies for their rhymes and songs.

Another isolated reference appears, place unknown, in 1915, with a third reference in Chicago in 1920. The thousands of Halloween postcards produced between the turn of the 20th century and the 1920s commonly show children but do not depict trick-or-treating. Ruth Edna Kelley , in her 1919 history of the holiday, The Book of Hallowe'en , makes no mention of such a custom in the chapter "Hallowe'en in America."

It does not seem to have become a widespread practice until the 1930s, with the earliest known uses in print of the term "trick or treat " appearing in 1934, and the first use in a national publication occurring in 1939. Thus, although a quarter million Scots-Irish immigrated to America between 1717 and 1770, the Irish Potato Famine brought almost a million immigrants in 1845–1849, and British and Irish immigration to America peaked in the 1880s, ritualized begging on Halloween was virtually unknown in America until generations later.

Trick-or-treating spread from the western United States eastward, stalled by sugar rationing that began in April 1942 during World War II and did not end until June 1947.

Early national attention to trick-or-treating was given in October 1947 issues of the children's magazines Jack and Jill and Children's Activities , and by Halloween episodes of the network radio programs The Baby Snooks Show in 1946 and The Jack Benny Show and The Adventures of Ozzie and Harriet in 1948.

The custom had become firmly established in popular culture by 1952, when Walt Disney portrayed it in the cartoon Trick or Treat, Ozzie and Harriet were besieged by trick-or-treaters on an episode of their television show, and UNICEF first conducted a national campaign for children to raise funds for the charity while trick-or-treating.

Although some popular histories of Halloween have characterized trick-or-treating as an adult invention to rechannel Halloween activities away from vandalism, nothing in the historical record supports this theory. To the contrary, adults, as reported in newspapers from the mid-1930s to the mid-1950s, typically saw it as a form of extortion, with reactions ranging from bemused indulgence to anger.

Likewise, as portrayed on radio shows, children would have to explain what trick-or-treating was to puzzled adults, and not the other way around. Sometimes even the children protested: for Halloween 1948, members of the Madison Square Boys Club in New York City carried a parade banner that read "American Boys Don't Beg."

In Scotland and parts of northern England, a similar tradition is called guising because of the disguise or costume worn by the children. Like trick-or-treating, it arose as a Halloween practice only in the twentieth century. However there is a significant difference from the way the practice has developed in the United States. In Scotland, the children are only supposed to receive treats if they perform for the households they go to.

This normally takes the form of singing a song or reciting a joke or a funny poem which the child has memorized before setting out. Occasionally a more talented child may do card tricks , play the mouth organ, or something even more impressive, but most children will earn plenty of treats even with something very simple.

However, guising is falling out of favour somewhat, being replaced in some parts of the country with the American form of trick-or-treating. Such a practice is in use in certain regions of the United States, as well. Children of the St. Louis, Missouri area are expected to preform a joke before receiving any candy.

In modern Ireland there is neither the Scottish party-piece nor the American jocular threat, just "treats" — in the form of apples or nuts given out to the children. However, in 19th and early 20th century Ireland it was often much more extravagant — for example, slates were placed over the chimney-pots of houses filling the rooms with smoke and field gates were lifted off their hinges and hung from high tree branches.

Until the 1990s, Irish children said "Help the Halloween Party," but are now more inclined to use the American "Trick or treat" due to the influence of American popular culture, movies, and television. In Waterford, the phrase "attin far Halloween" is still commonly used, being the vernacular pronunciation of "anything for Halloween".

In Quebec, Canada, children also go door to door on Halloween. However, in French speaking neighbourhoods, instead of "Trick or treat?" , they will simply say "Halloween", though in tradition it used to be La charité s'il-vous-plaît (Charity, please).