PR will engage your internal publics (employees) because they hold a vital stake in the image of the brands. And engaging the external publics (clients and customers) to earn loyalty and trust for the brand. Other relationship with the media, community of operation with effective and appropriate tools are all duty of a PR unit in an organization.
Public Relations relate with the publics because it functions for both personalities and brands. Every personality and brand live in the human society and they relate with people – publics. For a brand, you know there are people working within the organization for the business. In the same way, their activities within the organization are for a particular category of people – public.