Leadership is the process of motivating a group of people to act towards accomplishing a common task. There are number of recognized versions, or styles, of leadership, some of which have been shown to be more effective than others. In 1939, a group of researchers led by German-American psychologist Kurt Lewin identified three major leadership styles: authoritarian or autocratic; participative or democratic; and delegative. Good leaders may well adopt some element of all of the styles of leadership.