Nudge theory is a concept in behavioral economics that suggests small changes in the way choices are presented can significantly influence people's decisions. By subtly guiding individuals toward certain behaviors without restricting their options, nudges can promote better choices in areas like health, finance, and environmental sustainability. For example, placing healthier food options at eye level in a cafeteria can encourage better eating habits. This approach relies on understanding human psychology and the factors that affect decision-making, as highlighted by researchers like Richard Thaler and Cass Sunstein in their book, "Nudge."