This document discusses definitions of mental disorders and outlines three main approaches: deviance from social norms, difficulty adapting to life, and experience of personal distress. It notes advantages and limitations of each approach. The document also describes levels of severity from normal to mild, moderate and more severe disorders using examples of emotions, cognitions and behaviors related to difficulties with school grades. Additionally, it provides a brief overview of the history of abnormal psychology from ancient times to the present and defines types of prevention for mental disorders. Finally, the document discusses concepts of stigma, including self-stigma and public stigma, and provides examples of stereotypes, prejudices and discrimination related to mental illness.