Some children really take to this online medium, and some of those kids are socially completely competent, in fact, they've found that - extroverts - there is a correlation between extroversion and number of friends online, so if you have a lot of friends offline, you will probably have a lot of friends online. Other kids are introverts, and they are shy and they are quiet, they may have social anxiety and they may only feel comfortable expressing themselves online. Looking at someone face-to-face may be very challenging, so ultimately you have to know your child. Children who have autism, for example, children who have difficulty actually communicating in that way; they have found it is easier for them to communicate online, because it feels safer; you don't have to look someone in the face, so maybe it's not a bad thing. Maybe it's a way for your child to express themselves socially to get closer to someone, so you feel more comfortable to practice social learning, through the use of this tool. Ultimately the way you know it's a problem, again, is if they have problems offline socially. If they don't have any relations socially, if they are not having face-to-face time with some of those friends, then you may want to check this out and talk to them about how to express themselves more intimately face-to-face with people, but for many kids it's not really a problem.