Children's internet images warning by the Internet Watch Foundation
The Internet Watch Foundation says more needs to be done to educate young people about the dangers of putting sexually explicit images and videos online.
It is after a new survey found, for the first time, children below the age of 15 posting the content of themselves online.
The study, conducted over a three month period, found more than 3,800 images and videos online.
Nearly a fifth of them were of children under 15 - with some as young as six and seven.
The foundation says the study should be a "wake up call" for parents and people who work with children.
Louise from south Wales - not her real name - was nine when she first started posting images of herself online.
She told BBC Radio 1 Newsbeat that it continued for many years.