Earlier, New Year used to be celebrated on April 1st. Then a new calendar was adopted where New Year was celebrated on January. In the beginning, people did not accept 1st January as the New Year and continued to celebrate New Year on 1st April. They used to exchange gifts on New Year, so some people started to play a prank by giving mock gifts to people still celebrating New Year on 1st April. People who accepted these gifts were called April Fools. The idea of April Fools soon spread throughout the world. People then started pulling each other's legs by playing stupid pranks.