Violence among teenagers may be grabbing the headlines, but for many concerned with child protection it's virtual aggression that's the biggest emerging threat.

Cyberbullies use mobile phones or emails to send sexist, homophobic and racist messages, or they attack other differences - from physical and mental disabilities to victims' cultural or religious background, appearance, wealth or class. In some cases, bullies physically assault other children, then post images of fights online or distribute video recordings using text messages.

Caroline Cockerill, Symantec's internet safety advocate, is well aware of the problem. "Cyberbullies tend to use the same tactics as they do in the offline world," she says. "They torment other kids from a distance using email, websites, online games, instant messaging, blogs and community sites such as MySpace and chatrooms. Online taunts sting just like they do offline, but internet bullies can stay anonymous more easily."

The impact of cyberbullying on children can be huge. One pupil explains: "No one understood what I was going through. I didn't know who was sending me these messages and I felt powerless to know what to do."

There's no doubt that cyberbullying can be devastating, Cockerill observes. "Some bullies harass targets with a barrage of instant messages: 'Everyone hates you' or 'You're a loser'," she says. "Others create websites that mock others, impersonate their targets to post fake dating adverts or hack into their email accounts."

And it's not just children who get bullied. Teachers suffer too. "Students put a horrendous accusation about me on their website," one teacher told us. "Within hours it seemed that the whole school had read this message."

Educators have years of experience to call on when handling violent bullying, but social networks, the internet and mobile phones are harder to police. Because they're relatively new manifestations, there’s little available information to help teachers cope.

So what can be done to detect, monitor and act against the cyberbullies?

At a glance:

Beating cyberbullying - intro

Government response to cyberbullying

Social networking - the dangers

Technology - the solution as well as the problem?

Monitoring, privacy and a change of culture

Top 10 tips for avoiding cyberbullying