How to Win Friends and Influence People is a self-help book written by Dale Carnegie, published in 1936. It is one of the best-selling books of all time. Carnegie had been conducting business education courses in New York since 1912. The book's core idea is that you can change other people's behaviour simply by changing your own. It teaches you the principles to better understand people, become a more likable person, improve relationships, win others over, and influence behaviour through leadership.