April Fool's Day began in France more that 400 years ago. Before then, people celebrated the new year on 1 April. The in 1582 the French King, Charles IX, changed the calendar. He moved the beginning of the year from 1 April to 1 January. After this,angone who celebrated the new year on 1 April was called an 'April fool'. People played jokes on these 'April fools'.