Trait theory is a psychological framework that focuses on identifying and measuring individual personality characteristics, known as traits. These traits are considered stable over time and influence behavior across various situations. Prominent psychologists, such as Gordon Allport and Raymond Cattell, contributed to the development of this theory by categorizing traits into different types, including cardinal, central, and secondary traits. One of the most well-known models within trait theory is the Big Five Personality Traits, which includes openness, conscientiousness, extraversion, agreeableness, and neuroticism. This model helps in understanding how these traits interact to shape an individual's personality and predict behavior, making it a valuable tool in psychology and personal development.