Windows PCs and Macs have pretty good parental monitoring features, but they are just the first steps...
If your children are spending too much time on the home computer screen, your can gain some control of their computer usage by using Windows’ and Mac parental monitoring features. Those features provide a good first step, but aren’t the entire solution. Many parents are aware of threats to their children online (cyberbullying, sexting, online predators to name a few) but few know the different ways they can help keep them safe.
Windows 8:

Everyone parent wants to be the "cool" parent. You don't want to be one of those parents who won't let their child have a Facebook account because
