Blackmail seems to be a term that's most applicable to adults and not applicable to children. But it's very applicable to children. Children online, when approached by a child sex offender, will be asked for a variety of things, not the least of which is information. That is their age, their name, where they live, where they go to school, what they like to do and who their friends are. When their relationship develops a little further and the child might send a picture or an image of themselves to an adult, that adult can use the information that they previously received to extort or coerce a child to send images of themselves that they otherwise would never send. So they've been blackmailed by information that they provided previously, or an innocent or innocuous pictures that they sent subsequently, that information was used to have them send images that they would never otherwise send.