Psychology is the scientific study of behavior and mental processes. Essentially, psychologists attempt to understand why and how people do what they do. The complexity of human thought and behavior demands consideration of multiple perspectives. Thus, there are many sub-fields in psychology, some of which include: cognition and learning, emotion, lifespan development, social influences, personality, psychological disorders, and the biological basis of thinking, feeling, and behaving. Psychologists apply their knowledge towards the betterment of the lives of individuals and society by such means as treatment interventions, parent education, analyzing the needs of workplace environments, and effecting policy changes for improving education, mental health services, family life, and the criminal justice system. Wherever there are people, psychology has a role in its efforts to understand and, hopefully, improve the highly complex dynamic known as the "human condition."