Personality encompasses a person's unique blend of behavioral, cognitive, and emotional patterns that shape their adaptation to life. These patterns are relatively stable but can evolve over time.  While a universally agreed-upon definition of personality is lacking, most theories focus on motivation and interactions with the environment.  Trait theories, like those developed by Raymond Cattell, define personality based on traits that predict behavior. In contrast, behaviorally-oriented approaches emphasize learning and habits. Regardless of perspective, most theories recognize the relative stability of personality. The study of personality psychology seeks to understand the underlying tendencies that drive individual behavioral differences.  Psychologists explore personality through various lenses, including biological, cognitive, learning, trait-based, psychodynamic, and humanistic perspectives.  The field's diverse approaches reflect the influence of prominent early theorists such as Sigmund Freud, Alfred Adler, Gordon Allport, Hans Eysenck, Abraham Maslow, and Carl Rogers.