Today Is April Fools Day
An observance which takes place in many western countries every April 1, traditionally known as April Fools' Day or All Fools' Day. It's a day when humor reigns and harmless pranks, practical jokes, and hoaxes are socially sanctioned. Customary practices range from simple tricks played on friends, family, and coworkers to elaborate media hoaxes concocted for mass consumption.
The origins of April Fools' Day are obscure. The most commonly cited theory holds that it dates from 1582, the year France adopted the Gregorian calender which shifted the observance of New Year's Day from the end of March to the first of January.
According to popular lore, some folks, out of ignorance, stubbornness, or both, continued to ring in the New Year on April 1 and were made the butt of jokes and pranks on account of their foolishness. This became an annual tradition which ultimately spread throughout Europe and other parts of the world.
A major weakness of the calendar-change theory is that it doesn't account for a historical record replete with traditions linking this time of year to merriment and tomfoolery dating all the way back to antiquity, and not just in the west.
The ancient Romans, for example, celebrated a festival on March 25 called Hilararia marking the occasion with masquerades and "general good cheer."
Holi, the Hindu "festival of colors" observed in early March with "general merrymaking" and the "loosening of social norms," is at least as old.
The Jewish festival of Purimu is also quite old. Coinciding with the advent of spring, it's celebrated every year with carnivals, costume-wearing, and pranks.
It's not unreasonable to suppose that the calendrical changes of the 16th and 17th centuries served more as an excuse to codify a general spirit of mirth already associated with springtime than as a direct inspiration for April Fools' Day. But we'll probably never really know.