Social Networking Sites

I think the social networking sites are unique in many ways and have some common functionality. The common thing that they have is that they are used to digitally exchange information over the internet. When I say digital I meant to say digital information in the form of music (Myspace),  video(YouTube ), pictures (Facebook) and notes(Twitter). This was my impression. And to a very large extent Myspace overlaps the layout of Facebook. YouTube is largely videos. And Twitter is largely used for status updates due to its limitation for 140 words.