The United Parcel Service (UPS) case in the previous unit illustrated the importance of communication.
Public Relations is: It is an ephemeral and wide-ranging field, often misperceived, and because of the lack of message control inherent in public relations, it is difficult to master.
The public relations function is prevalent and growing; you can find public relations in virtually every industry, government, and non-profit organization.
1 A conduit
2 A facilitator
3 A manager of communication
4 Conducting research
5 Defining problems
6 Creating meaning by fostering communication among many groups in society
7 A strategic conversation.
Public relations is “the management of communication between an organization and its publics.” 
As “the management of communication between an organization and its publics,” public relations has radically departed from its historical roots in publicity and journalism to become a management discipline—that is, one based on research and strategy.
The component parts of Grunig and Hunt’s famous definition of public relations are as follows:
Management: the body of knowledge on how best to coordinate the activities of an enterprise to achieve effectiveness.
Communication: not only sending a message to a receiver but also understanding the messages of others through listening and dialogue.
Organization: any group organized with a common purpose; in most cases, it is a business, a corporation, a governmental agency, or a non-profit group.
Publics: any group(s) of people held together by a common interest. They differ from audiences in that they often self-organize and do not have to attune to messages; publics differ from stakeholders in that they do not necessarily have a financial stake tying them to specific goals or consequences of the organization.
Targeted audiences, on the other hand, are publics who receive a specifically targeted message that is tailored to their interests.
Corporate and agency public relations differ.
It is not uncommon for a large corporation to have both an in-house corporate public relations department and an external public relations agency that consults on specific issues.
We can define corporate public relations as being an in-house public relations department within a for-profit organization of any size.
Public relations agencies are hired consultants that normally work on an hourly basis for specific campaigns or goals of the organization that hires them.
Non-profit public relations refers to not-for-profit organizations, foundations, and other issue- or cause-related groups.
Government relations or public affairs is the branch of public relations that specializes in managing relationships with governmental officials and regulatory agencies.
 Grunig, J. E., & Hunt, T. (1984). Managing public relations. New York: Holt, Rinehart and Winston.