Malala Yousafzai, the Pakistani girl shot by the Taliban, has told the UN that books and pens scare extremists, as she urged education for all.
Speaking on her 16th birthday, Malala said efforts to silence her had failed.
She was shot in the head on a school bus by Taliban gunmen because of her campaign for girls' rights.
The speech at the UN headquarters in New York was her first public address since last October's incident in Pakistan's north-western Swat valley.
Malala has been credited with bringing the issue of women's education to global attention. A quarter of young women around the world have not completed primary school.
After the shooting, Malala was flown from Pakistan to the UK for treatment, and now lives in Birmingham, England.
There were huge cheers when Malala Yousefzai took to the podium. A few months ago, such a moment might have seemed unimaginable. Her speech, to more than 500 young people aged 12-25 from around the world, was delivered with grace and compassion.
Malala may be the focus and inspiration behind today's events, but she hopes her message will highlight the challenges millions of her contemporaries face. Many here say she's their inspiration.
There is a buzz of excitement at the UN. Corridors and chambers normally filled with sharp-suited diplomats have, for one day at least, been taken over by teenagers. It's Malala's story and incredible recovery from her attack that have brought the issue of universal education to greater global attention. The challenge is to keep up the momentum to make a real change.
Amid several standing ovations, Malala told the UN on Friday that the Taliban's attack had only made her more resolute.
"The terrorists thought that they would change my aims and stop my ambitions," she said, "but nothing changed in my life, except this: weakness, fear and hopelessness died. Strength, power and courage was born."