The widely adopted, now classic book on influence and persuasion--a major national and international bestseller with more than four million copies sold! In this highly acclaimed New York Times bestseller, Dr. Cialdini--the seminal expert in the field of influence and persuasion--explains the psychology of why people say yes and how to apply these principles ethically in business and everyday situations. - You'll learn the six universal principles of influence and how to use them to become a skilled persuader--and, just as importantly, how to defend yourself against dishonest influence attempts: Reciprocation: The internal pull to repay what another person has provided us. - Understanding and applying the six principles ethically is cost-free and deceptively easy. Backed by Dr. Cialdini's 35 years of evidence-based, peer-reviewed scientific research--as well as by a three-year field study on what moves people to change behavior--Influence is a comprehensive guide to using these principles effectively to amplify your ability to change the behavior of others.