This paper deals with the topic of privacy protection on social networks, explores how acquainted the users are with the protection of personal data during their use. It is divided into two parts: the first part contains theoretical explanations and literature, while the second part contains the research carried out. The first part describes the historical development of social media and provides the descriptions of four social networks that are the center of research: Facebook, Instagram, LinkedIn and TikTok. Also, the basic determinants of GDPR are defined in order to define the legal basis for data protection. The research part of the paper presents the results of a survey conducted among 506 users of social media using a survey questionnaire. The aim of the survey was to show how users perceive the issue of privacy on social networks and how they adapt their behavior on social networks accordingly; if they are aware of the need for privacy protection and how important the protection of personal data they provide while using social networks is to them. The results obtained by this study show that the surveyed users of social networks are mostly cautious when sharing their personal data.