The purpose of this study is to explore the aspects of privacy over the use of social networks web sites. More specific, we will show the types of social networks, their privacy mechanisms that are different in each social network site, their privacy options that are offered to users. We will report some serious privacy violations incidents of the most popular social networks sites such as Facebook, Twitter, LinkedIn. Also, we will report some important surveys about social networks and preferences of their users. There is no denying that social networking has become a huge part of today’s information society. SNSs(Social Networks) are almost everywhere, examples include the largest ones; Facebook, Twitter, LinkedIn, Youtube. Driving the development of such services are often the anticipation of new features, cool tools, access to all sorts of data in all kinds of ways. People and enterprises are sharing more and more personal and sensitive data in search for social and organizational benefits or other ways to exploit these services fully. There are benefits to be reaped, but there are also negative consequences when it comes to privacy. Seeing as these services will handle vast amounts of personal and sensitive data they should have correspondingly strict access control requirements to protect the privacy of its users. When new features drive the development of these services, and there is a race for deploying them as fast as possible, privacy often suffers. Lack of privacy in some shape might even be a requirement for a service or feature to be able to work properly. This leads to the pattern where services are deployed without much concern for privacy, and when such concerns are raised, at a later point in time, privacy will be more or less addressed. This pattern exists because the developers of SNSs do not have adequate incentives for implementing strict access and privacy control, seeing as large portions of the public seems to not understand the risks or do not care about this kind of privacy (or they might not consider it an important enough factor in the choice of whether or not to use different kinds of SNSs). That is why one important further research area is a way to make the public understand privacy and the risks involved when sharing personal or sensitive information through SNSs. In addition to understanding the risks, the public should be able to check the privacy policies of an SNS (e.g. by using P3P plus easily understandable GUI interfaces to display a website’s privacy policies in a browser). This might create incentives for the developers of SNSs to include more strict access and privacy control in their product.