The Five-Factor Model (FFM) is a comprehensive taxonomy of personality traits, which are tendencies to show consistent patterns of thoughts, feelings, and actions. Although it was originally identified in the United States, the model appears to describe personality structure well in a wide variety of cultures, suggesting that personality trait structure is universal. Age changes--decreases in Neuroticism, Extraversion, and Openness and increases in Agreeableness and Conscientiousness from adolescence to adulthood--also appear to be universal, as are gender differences. Current studies comparing the mean levels of personality traits across cultures show systematic patterns, but their interpretation is uncertain. The FFM is currently in use by psychologists around the world in a variety of applications.