The true origin of April Fools' Day

The April 1 officially became the day of lying in the year 1501 as soon as the Portuguese arrived in Brazil on behalf of the Indians were playing with the settlers, deceiving them about the existence of gold in coastal land had been discovered. The joke was revealed, and the date ended up being registered as a day of lying.According to the Encyclopedia Britannica (now it's true), there are records of the April Fool jokes on this date by many centuries, and it can be compared to the Hilaria festival, celebrated on March 25 in Ancient Rome, or the Indian Holi celebration of 31 March.

Several versions
Encyclopedias and dictionaries of international culture are almost unanimous in saying that there is no official record of the history of April 1st as April Fools' Day, or a formal justification for the day be known this way in many countries, including Brazil, United States, Britain and France.
One explanation is commonly cited as the most accepted by historians. She goes back to the calendar used by the countries of Europe changed. Until 1564, the new year was celebrated on March 25, and the festivities were extended until the 1st of April, not January. It was this year that King Charles IX of France ordered the New Year would be celebrated on January 1, which caused great confusion in the country and continent.
Here come two versions. One says that some more conservative French decided to keep their celebrations at the end of March, being smeared by the rest of society. Another explanation, perhaps more realistic, remember the time that the media were precarious, so it took for the whole company knew about the change, causing confusion from being used for games that were created involving lies.
In fact, a historical research shows that the calendar change in the early sixteenth century was not as simple as it may seem confusing and became the organization of the different peoples of Europe. The French king's decree, signed in 1564, only took effect in 1567, 15 years before the Gregorian calendar reform of 1582. Some countries, like Britain, for example, continued celebrating the change of the year on March 25 for more than a century, but embracing the shift after 1751.
The Britannica says that since the French decree, those who continued celebrating the new year between March and April were called "fools" by encouraging games involving lies. The convention ended up spreading, with different names and traditions, but always involves making someone play the fool with lies.

so Happy April Fool's day joke or
Happy April 1st!