Carl Jung, a renowned psychologist, introduced the concepts of introversion and extraversion, which explore different personality traits and how individuals interact with the world. His theories emphasized the importance of unconscious processes and the balance between these two personality types. Jung proposed that introverts are inward-focused, deriving energy from solitary activities, while extraverts draw energy from social interactions. His work laid the foundation for modern psychology and enabled further exploration of personality theories, influencing fields such as psychotherapy and personal development.