Across situations and years, a person tends to be outgoing, organized, and prone to worry. Personality refers to those relatively enduring patterns of thoughts, feelings, and behaviors that distinguish one individual from another.

Trait models such as the Big Five—openness, conscientiousness, extraversion, agreeableness, neuroticism—provide a widely used descriptive framework. Psychodynamic, humanistic, and social-cognitive approaches offer complementary accounts of how personality develops and functions. Twin studies indicate substantial heritability, while life experiences and culture shape expression.

Personality predicts important life outcomes including relationship quality, occupational success, and health behaviors. It is not fixed; mean-level changes occur across the lifespan, and targeted interventions can shift traits to a degree. Assessment relies on self-report, informant ratings, and behavioral observation. Personality supplies the characteristic style with which a person meets the world.

Knowing someone’s personality allows partial prediction of how they will respond in new situations.