The problem of teenagers using mobile devices at school and at home, in terms of time and content accessed, can affect both parents and schools, especially with the emergence of the Internet, which is increasingly present on smartphones and tablets. The use of cell phones for personal use by adolescents aged between 15 and 17 in Brazil is 80.8%. In this context, the problem is to identify the effects of the mediation of mobile devices, especially in the teaching-learning process and family life, on high school adolescents in public and private schools. The book covers: internet and its use in Brazil; science, technology and society and digital technologies; cyberculture; school in cyberculture; use of smartphones by teenagers, teachers and parents; problems arising from the use of smartphones or tablets and the internet by teenagers, teachers and parents; academic performance of teenagers; risks with the use of digital technologies, such as radio frequency; mobile devices in disuse. The analysis should help students and professionals in the field of education and the social sciences.