Internet bullying has seen very few prosecutions, but causes daily misery for victims and can end in suicide. Social networking sites are hugely popular with British young people  -  about half are members, with 5.2 million 13 to 19-year-olds signed up to Facebook. It's a great way of swapping news and staying in touch, but the downside can be tremendous, with one in three saying they've been bullied online. Click here to find out more.