Halloween is a tradition celebrated on the night of October 31, most notably by children dressing in costumes and going door-to-door collecting sweets, fruit, and other treats. It is celebrated in parts of the Western world, most commonly in the United States, Canada, the UK, Ireland, and with increasing popularity in Australia and New Zealand, as well as the Philippines. In recent years, Halloween is also celebrated in parts of Western Europe, such as Belgium and France. Halloween originated as a Pagan festival among the Celts of Ireland and Great Britain with Irish, Scots, Welsh and other immigrants transporting versions of the tradition to North America in the 19th century. Most other Western countries have embraced Halloween as a part of American pop culture in the late 20th century.
The term Halloween, and its older spelling Hallowe'en, is shortened from All-hallow-even, as it is the evening before "All Hallows' Day" (also known as "All Saints' Day"). The holiday was a day of religious festivities in various northern European Pagan traditions, until Popes Gregory III and Gregory IV moved the old Christian feast of All Saints Day from May 13 to November 1. In Ireland, the name was All Hallows' Eve (often shortened to Hallow Eve), and though seldom used today, it is still a well-accepted label. The festival is also known as Samhain or Oíche Shamhna to the Irish, Calan Gaeaf to the Welsh, Allantide to the Cornish and Hop-tu-Naa to the Manx. Halloween is also called Pooky Night in some parts of Ireland, presumably named after the púca, a mischievous spirit.
Many European cultural traditions hold that Halloween is one of the liminal times of the year when spirits can make contact with the physical world and when magic is most potent (e.g. Catalan mythology about witches, Irish tales of the Sídhe).....
Halloween did not become a holiday in America until the 19th century, where lingering Puritan tradition meant even Christmas was scarcely observed before the 1800s. North American almanacs of the late 18th and early 19th centuries make no mention of Halloween in their lists of holidays. The transatlantic migration of nearly two million Irish following the Irish Potato Famine (1845–1849) brought the holiday and its customs to America. Scottish emigration from the British Isles, primarily to Canada before 1870 and to the United States thereafter, brought that country's own version of the holiday to North America.
When the holiday was observed in 19th-century America, it was generally in three ways. Scottish-American and Irish-American societies held dinners and balls that celebrated their heritages, with perhaps a recitation of Robert Burns' poem "Halloween" or a telling of Irish legends, much as Columbus Day celebrations were more about Italian-American heritage than Columbus. Home parties would center around children's activities, such as bobbing for apples and various divination games, particularly about future romance. And finally, pranks and mischief were common on Halloween....
There is little primary documentation of masking or costuming on Halloween in America, or elsewhere, before 1900. Mass-produced Halloween costumes did not appear in stores until the 1930s, and trick-or-treating became a fixture of the holiday in the 1950s, although commercially made masks were available earlier.