The history of April Fool's Day, sometimes called All Fool's Day, is not totally clear. There really wasn't a first April Fool's Day that can be pinpointed on the calendar. Some believe it evolved simultaneously in several cultures at the same time, from celebrations involving the first day of spring. The closest point in time that can be identified as the beginning of this tradition was in 1582, in France. Prior to that year, the new year was celebrated for eight days, beginning on March 25. The celebration culminated on April 1. With the reform of the calendar under Charles IX, the Gregorian Calendar was introduced, and New Year's Day was moved to January 1.
Communication being what it was in the days when news traveled by foot, many people did not receive the news for several years. Others, the more obstinate or "set in their ways" crowd, refused to accept the new calendar and continued to celebrate the new year on April 1. These folk were labeled fools by the general population. They were subject to ridicule, and were often sent on "fools errands" or were made the butt of practical jokes.
Over time, the harassment evolved into a tradition of prank-playing on the first day of April. It spread around the world and April Fool's Day became an international fun fest, so to speak, with different nationalities specializing in their own brand of humor at the expense of their friends and families.
April Fools Day is simply a fun little holiday, but a holiday on which you must remain forever vigilant. You don’t want to be an April Fool, do you?