Social psychology is the scientific study of how individuals behave and think in social situations and how they interact with and influence others. Some key topics in social psychology include conformity, obedience, attitudes, persuasion, group processes, prejudice, aggression, and interpersonal relationships. Social psychology was introduced in the late 19th century to understand human behavior and phenomena like extreme obedience. It uses scientific methods to study how people's thoughts, feelings, and behaviors are influenced by real or imagined presence of others.