April 1st is celebrated as Fools' Day and on this day, people play pranks on each other. April Fools' Day, which falls on the first day of April is also known as All Fools' Day. The day was first celebrated in France after the European nation stopped using the Gregorian calendar. By doing this, France switched New Year's Day from Apr. 1 to Jan. 1, but many continued celebrating the new year on the first of April. Those who celebrated in April were considered to be "fools" and people would play tricks on them. In France, the day is called "Poisson d'Avril," which means "April fish". Take a look at some April Fools' Day pranks.