There is no doubt that the Internet has profoundly modified our daily life, in particular becoming an integral part of young people’s life and activities. It is a source for information, a new channel of communication and it is used for various leisure activities. On the other hand, it also carries a potential threat to people’s mental health, when people spend excessive amount of time on its use and when time spent gaming online tends to prevail when compared to other activities. The peak time spent on Internet gaming is increasing in young people, with near to 11 hours per day. Computer gaming has been conceptualized as continuum from an enjoyable activity to a pathological and an addictive use. In the new version of the International Classification of Diseases (ICD-11), Gaming Disorder (GD) has been included in the chapter of mental and behavioural disorders. Prevalence rates of Internet Gaming Disorder (IGD) range from 0.2% to 50%, but the true extent of the phenomenon is not yet known due to the lack of specific diagnostic criteria prior to the publication of ICD-11. The inclusion of this new disorder has generated keen debate and raised controversies in the scientific community. Like most behavioural disorders where pathology is identified by variation in norms, it would appear that there is a clear need to define an appropriate boundary between normal Internet gaming and IGD. We believe that considering IGD as proper mental disorder may generate a common ground for assessment, research and development of appropriate treatments. However, high-quality longitudinal multicenter studies are urgently needed in order to identify possible biomarkers of this new disorder and to understand the developmental trajectory of IGD.