So why is today ?April Fool?s Day?
Ancient cultures, including those as varied as the Romans and the Hindu, celebrated New Year?s Day on 1 April. It closely follows the vernal equinox (20 March or 21 March). In medieval times, much of Europe celebrated 25 March, the Feast of Annunciation, as the beginning of the new year.

In 1582, Pope Gregory XIII ordered a new calendar (the Gregorian Calendar) to replace the old Julian Calendar. The new calendar called for New Year?s Day to be celebrated on 1 January.

As communication travelled slowly in those days there were some people who hadn?t heard or didn?t believe the change in the date so they continued to celebrate New Year?s Day on 1 April. These people were labelled "fools' by the general populace and were subject to ridicule and practical jokes. This custom has continued to this day.