This paper deals with the topic of personal data protection on the Internet. Therefore, the first part of the paper analyzes and explains the concept of data protection, what is personal data and how it is processed. Furthermore, the General Data Protection Regulation, or GDPR, is analyzed, and the term GDPR itself is defined, as well as the rights based on which the Regulation is enacted. In addition to the GDPR, the Agency for the Protection of Personal Data in Croatia, i.e. AZOP, is also analysed, the mission, vision and specific tasks performed by the Agency are stated. The last part of the paper is based on quantitative research in the form of a survey. The research was done with the aim of better understanding the opinions and certain habits of respondents when using primarily social networks for some free purposes. In order to better understand the respondents' perception of personal data protection, the questions were perceived in a way that reveals how much knowledge the respondents have about the protection of personal data, and how aware they are of certain dangers that come with it. Furthermore, the analysis of the obtained data is presented, and a conclusion is written at the very end of the paper.