Various terms are used to refer to someone who works in public relations.
They include PR, agent, PR agent, publicist, public relations officer, PRO, PR consultant, spin doctor or even flack (which is used in the derogatory sense).
Publicists and PR agencies work either for personalities and companies, as a part of a team or independently as freelancers.
There are PR professionals in multiple fields like Bollywood, fashion, technology, corporate industries etc. They devise a branding strategy for their clients and help them stay in the limelight.