The history of April Fools' Day, sometimes called All Fools' Day, is not clear. There is no first "April Fools' Day" that can be pinpointed on the calendar, although it is known to date back at least to the sixteenth century. Most historians believe that April Fool’s Day originated in continental northern Europe and then spread to Britain.
Some popular theories on the origin of April Fools' Day include:
The Gregorian Calendar
Some say that April Fools' Day was first celebrated soon after the adoption of the Gregorian Calendar. Prior to that time, much of Europe celebrated March 25, the date of the Christian Feast of Annunciation, as the beginning of the new year. The celebration culminated on April 1 and was celebrated in much the same way as it is today with parties and dancing into the late hours of the night.
In 1563 King Charles IX decreed January 1 to be the first day of the year. Eighteen years later, in 1582, Pope Gregory XIII introduced the new Gregorian Calendar, and New Year's Day was moved to January 1. Upon moving the official New Year's Day from April 1 to January 1, there were some people who hadn't heard or didn't believe the change in the date, so they continued to celebrate New Year's Day on April first. These people were called them "April fools" and often had tricks played on them. They were subject to ridicule, and were often sent on "fools errands" or were made the butt of other practical jokes.
Although this is a popular and widespread theory, it is not the only theory for the origin of the holiday, and many of the customs and traditions of the holiday were already well established prior to the calendar change.
The Arrival of Spring
Some believe that the custom is related to the arrival of Spring with the unpredictable and capricious April weather.
Also, the Spring Equinox marks the end of winter and the beginning of spring and the new growing and planting season. Many cultures celebrated this time of year with jubilant festivals where people would wear disguises and play pranks on each other. Many historians believe April Fools' Day evolved from some of these festivals.
May Day (May 1)
In many pre-Christian cultures May the 1st (May Day), which falls approximately halfway between the spring equinox and summer solstice, was celebrated as the first day of summer. This marked the beginning of the new growing and planting season. Someone who did this prematurely would be called an April Fool.
Today, April Fools' Day has spread around the world, with different nationalities specializing in their own brand of humor at the expense of friends and families:
United States - Americans play small tricks on friends and strangers alike on the first of April. One common trick is pointing down to a friend's shoe and saying, "Your shoelace is untied."
France - French children fool their friends by taping a paper fish to their backs. When the young victim discovers this trick, the prankster yells "Poisson d'Avril!" (April Fish!)
England - Tricks can be played only in the morning. If a trick is played on you, you are a "noodle".
Scotland - April Fools' Day is actually celebrated for two days and the custom is known as "hunting the gowk" (the cuckoo), and April fools are "April gowks". The second day is devoted to pranks involving the posterior region of the body. It is called Taily Day. The origin of the "kick me" sign can be traced to this observance.
Spain – the counterpart of April Fools' Day is actually observed on December 28. Originally, the day was a sad remembrance of the slaughter of the innocent children by King Herod. It eventually evolved into a lighter commemoration involving pranks and trickery.
Portugal - April Fools' is celebrated on the Sunday and Monday before Lent. The traditional trick there is to throw flour at your friends.