While we've all been taught to beware of online predators, experts say that's just the beginning, when it comes to Internet dangers for girls.
websites that promote cyberbullying, eating disorders and sexualization can wreak havoc on a girl's self-esteem and health.
Like most teenage girls, Hannah and Mackenzie love to check their Facebook accounts or post photos. But one day one of Hannah's friends was brutally attacked online.
"They were making up rumors about her, calling her a whore," Hannah said, "saying she was ugly and she wasn't pretty and no one should like her and no one does like her."
Hannah's dad and Internet safety expert Sam Black said, "Here, this beautiful, smart intelligent well rounded young girl was being just sexually harassed and taunted at every turn."
Black knows firsthand what dangers lurk online for teen girls, including his daughter.
"Body image, sexualization of women and girls, cyber bullying, all these things can play out on the Internet."
Child safety expert Michele Borba said, "There are a number of new sites that look like they're harmless but are actually teaching our girls very, very vicious lifestyle changes. Formspring is one of the new kinds of websites that looks like a social network that is popping up online for our daughters. It looks tame enough. But once they log on, what it actually encourages instead, is to send vicious notes toward one another in an anonymous nature."
Formspring refused our request for an on camera interview, but in an email told us it takes safety and privacy very seriously and has developed practices for blocking inappropriate content. That's not the only site that concerns Michele Borba and Sam Black.
New online games where teens create and play highly sexualized characters are a shock. "For example, one is called the bimbo game. Breast implants, and if you earn a certain amount of points in life, you can even buy yourself a sugar daddy. Totally unhealthy and you do not want your daughters in any part of it," Borba said.
"These kinds of games only demean what girls think about themselves," Black said.
And then there are the websites that promote unhealthy lifestyle choices, such an anorexia and bulimia, with photographs of super skinny models and step by step tutorials.
"Specific directions on how to purge, how to purchase diet pills. And it is doing damage. Stanford University found that 96 percent of girls who are anorexic learned a lot of their eating habits on those sites," Borba said.
So how do parents keep their teens off these websites?
Our experts offer this advice: First - invest in parental control software monitor your teen's online history.
Do Google searches on their full names to see if anything comes up.
And limit their time online.
And take the time to get Internet savvy yourself.
It could make all the difference in your daughter's life.
"You need to step up to the plate," Borba said. "You need to monitor because we're raising our children in a tough world."
The makers of the Bimbo Game say the average age of their users is 19-years-old and insist their players know the difference between a game and reality.
That said, don't wait too long to talk to your kids. A national survey found 85 percent of 12 and 13 year olds have experience with cyber-bullying, with 53 percent saying they have been bullied online.