Resumen
The COVID-19 pandemic caused a transition to online services in almost all aspects of life. Today, online access is an important aspect of child well-being more than ever. The aim of the study was to investigate online activities and gender differences of children with a special focus on harmful online content, cyberbullying, and Internet addiction. Our research was conducted among students from one Croatian county (average age = 14.97, N = 494). The Internet Addiction Test, the European Cyberbullying Intervention Project Questionnaire, as well as questions constructed for the purposes of this research (e.g., online contents) were used. Between 20% and 30% of students spend four or more hours a day online. Furthermore, 14.57% of students showed moderate signs of addiction, and 1.42% already showed severe signs of addiction, where girls had significantly higher results. The results indicated that 12.75% of students were victims, 5.87% were perpetrators, and 8.3% were, at the same time, committing and experiencing cyberbullying. Children who commit and/or experience cyberbullying achieve higher results on the scale of Internet addiction than children who do not participate in cyberbullying. These findings contribute to our understanding of Internet usage and especially its problematic aspect in such a complex time as the COVID-19 pandemic, and they can be useful for planning future interventions with children.