A teenager in Bangladesh has won the International Children's Peace Prize for his efforts to educate young people about cyberbullying.
Sadat Rahman, 17, was inspired to create a mobile app to help young people report online abuse after hearing about a 15-year-old girl who took her own life because of bullying.
About 1,800 teenagers in his local district have now used the app.
Nobel laureate Malala Yousafzai described him as "an inspiration".
"He's calling on young people all over the world to stop cyberbullying and to help peers in their community who suffer from mental and emotional violence. Sadat is a true changemaker," she said in an online speech.
The International Children's Peace Prize is an annual award that recognises the work of young people who promote children's rights. Previous winners include Swedish climate activist Greta Thunberg.
Mr Rahman's app, Cyber Teens, allows young people to report cyberbullying confidentially through a network of volunteers who then approach police or social workers, while also educating teenagers about online safety.
Since its launch, more than 300 young victims of online crimes have been supported and eight people - including adults who sexually harassed children online - have been arrested.
The teenager plans to use the €100,000 (£90,000, $118,000) award to spread the app further in his home country "and hopefully to serve as a model for the rest of the world", according to the AFP news agency.
Accepting the award, Rahman explained that half of young internet users in Bangladesh had experienced cyberbullying and that fear and lack of knowledge had previously prevented many of them from reporting crimes.
"I strongly believe awareness, empathy, counselling and action are the four drivers of force to combat cyberbullying," he said. "The fight against cyberbullying is like a war, and in this war, I'm a warrior. If everybody keeps supporting me, then together, we will win this battle against cyberbullying."