What it is:
Theories of origin:
A major weakness of the calendar-change theory is that it fails to account for an historical record replete with traditions linking this time of year to merriment and tomfoolery dating all the way back to antiquity.
The Romans, for example, celebrated a festival on March 25 called Hilaria, 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.
It seems reasonable to speculate that the calendrical changes of the 16th and 17th centuries served more as an excuse to codify the general spirit of frivolity already associated with the advent of spring than as a direct inspiration.
Notable April Fools' Day pranks and hoaxes:
Some of the best-known pranks in recent years were mounted by advertising agencies. In 1996, Taco Bell ran a full-page ad in the New York Times announcing it had purchased the Liberty Bell and would rename it the "Taco Liberty Bell." Burger King pulled off a similar prank in 1998, announcing the rollout of its "Left-Handed Whopper" supposedly designed so that condiments would drip from the right side of the burger rather than the left.
On the Internet hoaxes have become such standard fare that April Fools' Day is barely distinguishable from any other, though a few notable pranks stand out and tend to be reposted year after year -- e.g., the 1996 announcement that every computer connected to the World Wide Web must be turned off for Internet Cleaning Day, a 24-hour period during which useless "flotsam and jetsam" are flushed from the system.
See also: The Atheists' Holiday
