This document summarizes a longer document about factors that influence human behavior and how understanding these factors can help develop effective communications strategies. It discusses three levels that influence behavior - personal, social, and environmental factors. Personal factors include knowledge, attitudes, habits, and beliefs. Social factors refer to interpersonal influences, and environmental factors include local and wider contextual influences. The document also provides overviews of behavioral economics principles and theories of behavior change. It emphasizes that to effectively influence behavior, communications strategies need to address factors at multiple levels rather than just focusing on one.