During the last few years, a steady stream of journal articles and conference papers with the aim of discerning the impact and possible meanings of social network sites (SNS) have been published. It is often argued that SNS significantly diverge from earlier forms of web communities since they are centred around the individual actor rather than themes of interest. According to boyd and Ellison (2007), an important aspect of these changes is that SNS allow for the construction of a public or semi-public profile through which it is possible to put on display a list of shared social connections which, in turn, makes it viable to browse the social connections of other users. By demonstrating the social connections to others, an establishment of latent social ties is facilitated and thus, as Haythorntwaite (2005) has demonstrated in depth, a form of connectivity emerges that makes otherwise unconnected others connect. Following these lines of thoughts, this paper aims at establishing an understanding of SNS which takes into account two interrelated yet hitherto undertheorised themes. First, SNS such as Facebook and Twitter, have largely come to function as mediators of social and symbolic content which in turn provide the basis for social interaction. Following the arguments of Knorr-Cetina (1997), among others, this paper explores the fact that communication on SNS occurs through a shared social object which is not only mediated but also structured thus allowing for a certain kind of object-centred sociability. Secondly, taking into account the emergence of such a sociability, this paper suggests that SNS are not so much mechanisms for self-presentation and social interaction as they can be regarded as social intermediaries which subject social and symbolic content to the specific structure of the digital interface. Taken as a whole, this paper provides an exploratory understanding of emerging social structures in digital culture thus illuminating important facets of social interaction and communication in contemporary society. 

boyd, d. m., & Ellison, N. B. (2007). Social Network Sites: Definition, History, and Scholarship. Journal of Computer-Mediated Communication, 13(1), 210-230. 

Cetina, K. K. (1997). Sociality with Objects: Social Relations in Postsocial Knowledge Societies. Theory, Culture & Society, 14(1), 1-30. 

Haythornthwaite, C. (2005). Social networks and Internet connectivity effects. Information, Communication & Society, 8(2), 125-148.