Already in 1954 the United Nations General Assembly recommended that all countries should dedicate a special day for observing the Children of the world, understanding of children and children's welfare. On November 20th 1959 the Assembly adopted the Declaration of the Rights of the Child and in 1989 the Convention on the Rights of the Child.
Extracts from Secretary-General's message for 2014:
"The one thing all children have in common is their rights. Every child has the right to survive and thrive, to be educated, to be free from violence and abuse, to participate and to be heard. "
"...we all have a common responsibility to uphold and protect those rights, which are fundamental to the strength of our societies. Together, let us stand up for the rights of children everywhere, for a more just and equitable world, and for a brighter future for all. "
the whole message can be read here.
HAPPY UNIVERSAL CHILDREN'S DAY!