April Fools' Day is celebrated in many countries on April 1 every year. Sometimes referred to as All Fools' Day, April 1 is not a national holiday, but is widely recognized and celebrated as a day when people play practical jokes and hoaxes on each other.
In Italy, France and Belgium, children and adults traditionally tack paper fishes on each other's back as a trick and shout "April fish!" in their local languages (pesce d'aprile!, poisson d'avril! and aprilvis! in Italian, French and Flemish, respectively).
The earliest recorded association between April 1 and foolishness can be found in Chaucer's Canterbury Tales (1392). Many writers suggest that the restoration of January 1 by Pope Gregory XIII as New Year's Day of the Gregorian Calendar in the 16th century was responsible for the creation of the holiday.
Precursors of April Fools' Day include the Roman festival of Hilaria, held March 25, and the Medieval Feast of Fools, held December 28, still a day on which pranks are played in Spanish-speaking countries.
In the Middle Ages, up until the late 18th century, New Year's Day was celebrated on March 25 (Feast of the Annunciation) in most European towns. In some areas of France, New Year's was a week-long holiday ending on April 1. Many writers suggest that April Fools originated because those who celebrated on January 1 made fun of those who celebrated on other dates. The use of January 1 as New Year's Day was common in France by the mid-16th century, and this date was adopted officially in 1564 by the Edict of Roussillon.
The April 1 tradition in France, Romandy and French-speaking Canada includes poisson d'avril (literally "April's fish"), attempting to attach a paper fish to the victim's back without being noticed. This is also widespread in other nations, such as Italy, where the term Pesce d'aprile (literally "April's fish") is also used to refer to any jokes done during the day. This custom also exists in certain areas of Belgium, including the province of Antwerp. The Flemish tradition is for children to lock out their parents or teachers, only letting them in if they promise to bring treats the same evening or the next day.