Excessive and pathological uses of the Internet are observed and discussed often in our modern conversations. Access to the Internet has become so convenient that these behaviors can lead to consequences in many areas of our lives from social relationships to academic and professional work performance. A common term that people use to address this pattern of behaviors is “Internet Addiction” or more specific ones, such as “Social Media Addiction” or “Online Gaming Addiction.” However, in clinical psychology, addiction has its own specific definitions. It refers to a category and set of criteria that are distinguished from other mental disorders in terms of symptoms, neurobiological processes, and treatment. Excessive use of the Internet per se is not enough to be addressed as an addiction. This literature review aims to present the established features of addiction from a behavioral level to a neurobiological level and compare them to the phenomenon of excessive and pathological Internet use. The goal is to explain why or why we should address not the problems of excessive and pathological Internet use as an addiction. For our purpose, the term “pathological Internet use” will be used in this literature review to indicate all the excessive and pathological Internet-related activities that are considered for the addiction model. After examining research on this subject, it is clear that excessive and pathological use of the Internet does share similar pattern of behavioral symptoms with typical drug addictions and gambling addiction. On the neuro-biological level, existing findings show relevant changes in a reward circuit that are responsible for addiction processes in the brain. However, more studies on the neuro-biological process are still needed to establish the enough evidence or addiction model to be applicable to pathological Internet use so that proper treatment can follow.