Halloween is celebrated on the night of October 31, most notably by children dressing in costumes and going door-to-door collecting sweets or money. It is celebrated in countries such as United States, Puerto Rico, the Republic of Ireland, the United Kingdom, Australia and Canada. Irish, Scots and other immigrants brought older versions of the tradition to North America in the 19th century. Most other Western countries have embraced Halloween as a part of American culture in the late 20th century. It has mostly being introduce in these countries at schools where English is taught as a second language.

The term Halloween is shortened from All-hallow-even, as it is the evening before "All Hallows Day". In Ireland, the name was All Hallows Eve and this name is still used by some older people. Halloween was also sometimes called All Saints' Eve.. In Mexico November 1st and 2nd are celebrated as the Day of the Dead.
Halloween is also called Pooky Night in some parts of Ireland, presumably named after the púca, a mischievous spirit.