It's about communication...

 Social networking sites "allow for creative expression in a new medium." In addition to that, social networking sites "bring people with the same interests together." It creates the atmosphere of an online community, which makes users feel included and wanted. It allows users who aren't very sociable or are a bit on the "shy side" to express themselves "through the windows of the computer screen." 

To add to the above,  "it is evident that the main use of social networking sites is interaction and communicating with others." This is because you "are more in contact with people than you would be otherwise." There are a lot of people you can "consider your friends,"  most have friends who are not from the same country. Even if you are from the other side of the world you are still considerably friends, of course if you've never met them or never will, you still communicate as if you've known each other for a while which maintains that relationship you have between one another.