April Fool's Day or all Fool's Day is the first of April. The fun of the holiday is to play silly but harmless jokes on family members and friends. The victim of these jokes is called an April fool. This holiday first appeared in France when the French began to use the Gregorian calendar, some people continued to use the old calendar and to celebrate New Year's Day in April 1. These people were called April fools. Playing jokes on this day became popular first in France and then in many other countries. Today, April Fool's jokes are played mostly by children, who enjoy the holiday very much.