The Aim of this thesis is to find out how Facebook affects children, whether they use it for useful purposes, or just for fun and social communication. Furthermore, the objective is to investigate the frequency and extent of Facebook usage. In addition, this study deals with the children's level of awareness of the danger arising from using Facebook or other popular social networks such as Instagram, Twitter, Snapchat, Myspace etc. Today's use of social networks is one of the most common activities of children. Any Web site that approves social interraction is called a social networking site, including social networks such as Facbook, Instagram, Snapchat etc. Such sites offer today's children a portal for entertainment and social communication, but also education. In recent years they have grown exponentialy. This paper includes the research study on the Facebook effects on children. The survey was conducted among 123 respondents, sixth, seventh and eighth grade students of two Elementary Schools: Elementary School July Kempf and Catholic Elementary School.