Psychology is the scientific study of the mind and behavior. Psychology is a multifaceted discipline and includes many sub-fields of study such areas as human development, sports, health, clinical, social behavior and cognitive processes.Psychology is the study of people's behavior, performance, and mental operations. It also refers to the application of the knowledge, which can be used to understand events, treat mental health issues, and improve education, employment, and relationships.They apply psychological science to understand how we make decisions and perceive our world. Developmental psychologists study how people grow and adapt over the course of their lives. They apply their research to help people overcome developmental challenges and reach their full potential.