April Fools' Day (sometimes called All Fools' Day) is celebrated every year on 1 April by playing practical jokes and spreading hoaxes. The jokes and their victims are called April fools. People playing April Fool jokes expose their prank by shouting April Fool. Some newspapers, magazines, and other published media report fake stories, which are usually explained the next day or below the news section in small letters. Although popular since the 19th century, the day is not a public holiday in any country.
Read more here.