James Grunig developed the four models of public relations: 1) Press agentry/publicity model uses propaganda and one-way communication to influence audiences. 2) Public information model distributes information through press releases. 3) Two-way asymmetrical model uses persuasion and manipulation through two-way communication to influence audiences. 4) Two-way symmetrical model uses two-way communication to promote mutual understanding between organizations and their publics. The models are used by different types of organizations, with the public information model being most common in the U.S. at 50% usage.