The World Conference for the Well-being of Children in Geneva, Switzerland, proclaimed June 1 to be International Children's Day in 1925. After the conference, different governments around the world decided to declare a day as Children's Day to draw attention to children's issues. Many countries chose June 1, so this is the reason, why International Children's Day take place an June 1.
It is usually marked with speeches on children's rights and wellbeing, and other events involving or dedicated to children.
A similar event, Universal Children's Day, falls on 20 November. It was established by the United Nations in 1954 and aims to promote the welfare of children around the world. On October 1953, Children’s Day was celebrated for the first time in Geneva with International Union for Child Welfare as the sponsor. This Children’s Day celebration inspired United Nations General Assembly to observe Universal Children’s Day in 1954.