This document provides an introduction to abnormal psychology, psychological disorders, and depression. It begins with defining key terms like abnormal and disorder, and discusses why these definitions are important but also tricky. It then explores different ways of defining abnormal behavior, including deviations from social norms, mental health, and ability to function. The document also discusses what makes a behavior considered abnormal and provides examples of mental disorders. It covers how psychologists diagnose disorders using the DSM manual and different approaches to understanding medical disorders. Specific topics related to depression are then outlined, including symptoms, causes, diagnosis process, and treatment options.