Moral development focuses on the emergence, change, and understanding of morality from infancy through adulthood. Morality develops across a lifetime and is influenced by an individual's experiences and their behavior when faced with moral issues through different periods' physical and cognitive development. In short, morality concerns an individual's growing sense of what is right and wrong; it is for this reason that young children have different moral judgement and character than that of a grown adult. Morality in itself is often a synonym for 'rightness' or 'goodness'. It refers to a certain code of conduct that is derived from one's culture, religion or personal philosophy that guides one's actions, behaviors and thoughts. This term is related to psychology. There are other types of development such as social development, physical development and cognitive development. Notions of morality development have been developed over centuries, the earliest came from philosophers like Confucius, Aristotle, and Rousseau, who all took a more humanist perspective and focused on the development of the conscience and sense of virtue. In the modern day, empirical research has explored morality through a moral psychology lens by theorists like Sigmund Freud and its relation to cognitive development by theorists like Jean Piaget, Lawrence Kohlberg, B. F. Skinner, Carol Gilligan and Judith Smetana. The interest in morality spans many disciplines (e.g., philosophy, economics, biology, and political science) and specializations within psychology (e.g., social, cognitive, and cultural). In order to investigate how individuals understand morality, it is essential to consider their beliefs, emotions, attitudes, and behaviors that contribute to their moral understanding. Additionally, researchers in the field of moral development consider the role of peers and parents in facilitating moral development, the role of conscience and values, socialization and cultural influences, empathy and altruism, and positive development, in order to understand what factors impact morality of an individual more completely. Freud: Morality and the Superego: The founder of psychoanalysis, Sigmund Freud, proposed the existence of a tension between the needs of society and the individual. According to Freud, moral development proceeds when the individual's selfish desires are repressed and replaced by the values of important socializing agents in one's life (for instance, one's parents). B.F. Skinner's Behavioral Theory: A proponent of behaviorism, B.F. Skinner similarly focused on socialization as the primary force behind moral development. In contrast to Freud's notion of a struggle between internal and external forces, Skinner focused on the power of external forces (reinforcement contingencies) to shape an individual's development. Piaget's Theory of Moral Development : While both Freud and Skinner focused on the external forces that bear on morality (parents in the case of Freud, and behavioral contingencies in the case of Skinner), Jean Piaget (1965) focused on the individual's construction, construal, and interpretation of morality from a social-cognitive and social-emotional perspective. To understand adult morality, Piaget believed that it was necessary to study both how morality manifests in the child's world as well as the factors that contribute to the emergence of central moral concepts such as welfare, justice, and rights. Interviewing children using the Clinical Interview Method, Piaget (1965) found that young children were focused on authority mandates, and that with age children become autonomous, evaluating actions from a set of independent principles of morality. Piaget characterizes the development of morality of children through observing children while playing games to see if rules are followed. Social Domain Theory: Elliot Turiel argued for a social domain approach to social cognition, delineating how individuals differentiate moral (fairness, equality, justice), societal (conventions, group functioning, traditions), and psychological (personal, individual prerogative) concepts from early in development throughout the lifespan. Over the past 40 years, research findings have supported this model, demonstrating how children, adolescents, and adults differentiate moral rules from conventional rules, identify the personal domain as a nonregulated domain, and evaluate multifaceted (or complex) situations that involve more than one domain. This research has been conducted in a wide range of countries (Argentina, Australia, Brazil, Canada, China, Colombia, Germany, Hong Kong, India, Italy, Japan, Korea, Nigeria, Spain, Switzerland, Turkey, U.K., U.S., Virgin Islands) and with rural and urban children, for low and high income communities, and traditional and modern cultures. Turiel's social domain theory showed that children were actually younger in developing moral standards than past psychologists predicted. Kohlberg: Moral Reasoning: Lawrence Kohlberg was inspired by the works of Jean Piaget and John Dewey.