I think that all depends on the maturity and responsiblity of each individual child. I think that at no matter what age you let your child use the internet they should always be monitered closely. You should always have control of their passwords, at least in my opinion. My children were all about 10 when they started to use the internet. They were very closely monitered. My oldest is 17 and she is still closely monitered, although I know kids can be sneaky. :) It is just so widely used in schools that it really benefits your children to know how to use a computer and the internet responsibly and correctly.