Mobile phone and Internet addiction refers to a person’s inability to control mobile and Internet use. An excessive use of mobile phone and Internet is associated with several complications related to psychological and emotional characteristics such as depression, loneliness, social anxiety and impulsivity. It can lead to an imbalance of chemicals in the brain and can hinder the cognitive capacity of a person. There are several criteria used for diagnosing mobile and Internet addiction. These can be primarily classified as behavioral and functional criteria. The major indicator is the persistent desire and/or unsuccessful attempts to quit or reduce smartphone use. Some of the preventive measures include monitoring the cell mobile phone and Internet use, engaging in mood-boosting activities, counseling, and mental health treatment. This book outlines the evaluation and prevention of mobile phone and Internet addiction in detail. Its extensive content provides the readers with a thorough understanding of the subject.