This document defines personality and discusses several theories and models of personality. It describes personality as a set of stable characteristics that influence behavior. It lists biological, cultural, family, social, and situational factors as determinants of personality. Three personality theories are outlined - trait theory, neo-Freudian theory, and self-concept theory. Freud's ID, ego, and super-ego model is presented. The Big Five personality traits and Myers-Briggs Type Indicator are explained. Additional personality attributes like locus of control, self-esteem, self-monitoring, and risk propensity are defined.