International  day of the girl began on December 19, 2011,  when the United Nations General Assembly adopted Resolution 66/170 to declare 11 October as the International Day of the Girl Child, to recognize girls’ rights and the unique challenges girls face around the world. This year the theme of the day was, Empowering Adolescent Girls: Ending the cycle of violence.

More information :http://www.un.org/en/events/girlchild/