April fool’s Day sometimes called All Fools' Day, one of the most light-hearted days of the year, which is observed throughout the Western world. Practices include sending someone on a "fool's errand," looking for things that don't exist; playing pranks; and trying to get people to believe ridiculous things. Its exact origins remain a mystery. Some historians speculate that April Fools’ Day dates back to 1582, when France switched from the Julian calendar to the Gregorian calendar, as called for by the Council of Trent in 1563. People who were slow to get the news or failed to recognize that the start of the New Year had moved to January 1 and continued to celebrate it during the last week of March through April 1 became the butt of jokes and hoaxes. These included having paper fish placed on their backs and being referred to as “poisson d’avril” (April fish), said to symbolize a young, easily caught fish and a gullible person.
Historians have also linked April Fools’ Day to ancient festivals as Ancient cultures including those of the Romans and Hindus, celebrated New Year's Day on or around April 1. It closely follows the vernal equinox (March 20th or March 21st.) and involved people dressing up in disguises. There’s also speculation that April Fools’ Day was tied to the vernal equinox, or first day of spring in the Northern Hemisphere, when Mother Nature fooled people with changing, unpredictable weather. Eventually, the practice spread throughout.