The concept of cognitive dissonance was developed by Leon Festinger. Introduced in 1957, this psychological theory explains the discomfort individuals experience when holding contradictory beliefs or values. Festinger's work illustrated how people strive for internal consistency; when faced with conflicting information, they may change their attitudes or rationalize their behaviors to alleviate discomfort. This theory has extensive implications in various fields, including psychology, marketing, and social behavior, shedding light on how individuals cope with cognitive conflict and make decisions in their lives.