What's the Origin<br />of April Fools' Day?.<br />The April 1 tradition of pranks has been observed<br />for several centuries across a variety of cultures.<br />However, the official origins of <br />April Fools’ Day are unknown.<br />The most popular theory is that the day was<br />caused by the switch from the Julian calendar<br />to the Gregorian calendar in the 16th century.<br />The original calendar saw the New Year<br />beginning on March 25, with celebrations<br />occurring on the first day of April.<br />The switch moved the New Year to January 1,<br />but many still thought April 1 was the proper day<br />to celebrate, hence they were “April fools.”.<br />Another theory says the day is related<br />to the arrival of Spring, when nature<br />“fools” people with irregular weather.<br />Historians have also linked April Fools' Day to an<br />ancient Roman festival known as Hilaria, which<br />was celebrated by people dressing up in disguises.<br />Whatever its origin may be, April Fools’ Day<br />has evolved to have its own lore and rules.<br />Superstition says that playing pranks<br />past noon or not responding to pranks<br />with good humor will attract bad luck