This master's thesis deals with issue of cyberbullying. It reports comprehensive view of the phenomen, whose severity has an increasing tendency, in particular thanks to continuous technical progress and development in the field of information and communication technologies. It characterizes particular tools, describes a specific form the resulting risks, which can develop through using the Internet and other digital media. It deals with the effects of cyberbullying to the psychic of the adolescents and brings a comprehensive view and experiences of children and adolescents with this issue. It focuses on the differences in the perception of cyberbullying by children and adults and on the role of social worker in the process of prevention and solution of cyberbullying.