Pakistani schoolgirl Malala Yousafzai shot by the Taliban in 2012, has called for free education for all children.
She gave the speech on her 16th birthday, at the United Nations headquarters in New York City, America.
It was her first time speaking in public since she was shot in the head by Taliban gunmen, while on her way to school in Pakistan in October.
Malala said the Taliban's attack changed nothing in her life, except "weakness, fear and hopelessness died".
"The extremists were, and they are, afraid of books and pens," Malala said. "They are afraid of women."
She said she was fighting for the rights of women because "they are the ones who suffer the most".
She called on politicians to take urgent action to ensure every child in the world has the right to go to school.
'One child can change the world'
"Let us pick up our books and pens," Malala said. "They are our most powerful weapons.
"One child, one teacher, one pen and one book can change the world.
"Education is the only solution. Education first."
After the shooting Malala was flown from Pakistan to the UK for treatment, and now lives and goes to school in Birmingham.
A 'hero and champion'
The head of the UN, Secretary General Ban Ki-moon, also addressed Friday's session.
Calling Malala "our hero" and "our champion", he said: "She is calling on us to keep our promises, invest in young people and put education first."
Malala has been credited with bringing the issue of women's education to global attention.
About 57m people around the world still do not have access to education, and a quarter of young women have not completed primary school.
In March 2013 Malala was nominated for the Nobel Peace Prize, one of the most respected and prestigious awards in the world.