Keeping youngsters safe online is one of the biggest child protection issues of the modern world, campaigners have warned.
Children should be given lessons in how to use the internet safely from as young as five or six amid concerns that rising numbers of youngsters are being exposed to online pornography, cyberbullying and forced into sending indecent images to others.
Young people are now experiencing new forms of abuse "on a scale never before seen", according to the NSPCC.
The charity said that its latest research had found that abuse through mobile phones and the internet is one of the major issues facing young people today.
In total, ChildLine conducted around 3,745 counselling sessions last year over these issues, with a further 250 contacts from children who said they were being "groomed" online. There was also an increase in calls about online pornography, with some from children as young as 11, the NSPCC said.
It added that previous research had shown that many teenagers see "sexting" and hardcore pornography as the norm, with some describing it as "mundane", and that some young people had been blackmailed or coerced into sending indecent images of themselves to strangers or other youngsters.
The charity is calling for all schools to provide age-appropriate lessons in online safety, with pupils themselves sharing advice on how to stay safe.
It also says that parents should have access to information to talk to their children about using the internet as they would drugs or the danger of strangers.
The call comes on Safer Internet Day, which promotes the responsible use of online technology and mobile phones for children and young people.
Claire Lilley, from the NSPCC, said: "Young people tell us they are experiencing all sorts of new forms of abuse on a scale never before seen. It's now clear that we are facing an e-safety timebomb, with this being one of the biggest child protection issues of our time."