Investigators of personality study how and why people, who all share a common human nature, are, at the same time all unique individuals. The first part of the question can be rephrased as "What is human nature?" OR, "What is the structure of the human personality that everyone shares?" The second part can be put as "How do important differences among people arise?" YES, the science of personality can be defined as the study of consistent patterns of individual differences in human behavior and experience. In this website, we will tackle five major approaches to personality which is-- trait, psychoanalytic, sociobiological, behavioral or social learning, phenomenological. Each set of these theories has value and was developed independently, so they shall be considered separately. At the end of the discussion we will synthesize them because we believe that the phenomenon of personality is captured more fully by a combination of the approaches than by each in isolation.