While April 1st, better known as April Fool's Day, is technically not a holiday, it is a favorite day for many a child or child at heart. It is believed that April Fool's Day traces its origins back to 1582, when the Julian calendar system (which said the New Year started in April) was replaced with the Greogorian calendar system that we use today. No matter how it all started, the day can be a lot of fun!