Abstract : Social Networks are in today's world an essential tool of communication. Everyday witnesses the birth of tens of new networks, occupying the airwaves with their chronicles, and becoming the subject of books, television programs and press articles. The impulsive rise of this multi-purpose communication tool is winning the attention of actors of different areas of interest (public, political...). As a socio-technical device, the social networks, being user-friendly and easy to implement, established themselves as a means of support, promoting exchange; sharing (of photos, videos, links); interaction and distribution of information of any kind. The first part of this thesis deals, from a historic perspective, with the usage of the notion ―network‖; ―social network‖ and ―social network sites‖. We will accompany the alteration in the usage of these terms, which occurred with time. Also, we will describe the social networks and compare them to other possibilities of web 2.0. Based on philosophical and theoretical approaches, the second part attempts to build a theoretical pattern of analysis, with man and technology being its fundamental dimension. Next to that is the analysis of the research material from an empirical/descriptive and exploratory approach. This allows us, on one hand, to elaborate on new typologies and categories of networks; and on the other, to sketch the cartography of the different controversies surrounding this complex communicational item.