The annual April Fools' Day Backwards Mile race in New YorkReuters

April Fools' Day, or All Fools' Day, is celebrated as the day when people play practical jokes and hoaxes on each other. It is not a national holiday, yet the day is highly popular and prompts wildly imaginative stories believed by thousands of people.

The origins of the day are murky. It has been cited, in one form or another, across all forms of popular culture.

Last year, Twitter announced that it would be charging tweeters to use vowels, while consonants were free - with the exception of the letter Y. In 2013, the Times ran an article about Nasa capturing an asteroid, while the Daily Mail dedicated an article entirely to Asda's Fifty Shades of Grey toilet paper - although it could well have been real, considering the paper once dedicated an entire story to the reality television star Lauren Goodger stepping over a puddle in Essex.

But, laughs aside, where did April Fools' Day come from?

It has been suggested that Geoffrey Chaucer's The Nun's Priest's Tale, written in the 1390s, is the earliest reference to April Fool with the story of a vain cock called Chauntecler who falls for the tricks of a fox.

The story is set "Syn March bigan thritty dayes and two" - which scholars have suggested is a veiled reference to 1st April ("since March began thirty-two days ago"). The ambiguous choice of words have led others to believe Chaucer meant May 3rd, which would be 32 days after March "was complet".

April Fools' Day has also been referenced in 16th and 17th century poetry. In 1508, the French poet Eloy d'Amerval wrote of a "poisson d'avril" - which translates as an April fool, literally an "April fish". The Flemish poet Eduard de Dene wrote about a nobleman who sent his servants on foolish errands on the day in 1539, while John Aubrey made the first British reference to "Fooles holy day" in 1686.

In the Middle Ages, New Year's Day was celebrated on 25 March in most European towns, as the Feast of the Annunciation. In some areas of France, it was a week-long holiday which ended on 1 April. Various writers have suggested April Fools originated because those who celebrated New Year on 1 January made fun of those who celebrated in March. The January celebration was officially adopted by France in 1564.

Where is it celebrated?

In Scotland, April Fools' Day is traditionally called Hunt-the-Gowk Day, the term "gowk" refers to a cuckoo or a foolish person. The traditional prank is to ask someone to deliver a sealed message requesting some sort of help. The message actually reads: "Dinna laugh, dinna smile. Hunt the gowk another mile" - to which the recipient will explain he can only help if he first contacts another person and the message is sent on.

In France and French-speaking areas of Canada, a paper fish is attached to the victim's back, known as the poisson d'Avril. The same tradition is carried out in Italy, as the Pesce d'aprile.

The Flemish tradition on April Fools' Day is for children to lock their parents or teachers out of the house or classroom, only letting them in if they promise to bring treats. In Poland, various hoaxes are prepared by the media - which sometimes make other information more credible. Serious jokes are avoided and the conviction is so strong that the anti-Turkish alliance with Leopold I - signed on 1 April 1683 - was backdated to 31st March.

Iran holds the oldest joke tradition, dating back to 536BC. The jokes are played on the 13th day of the Persian new year, Sizdah Be-dar, which falls on 1 April. Many believe this is the true origin.