So, what is PR then?

At a party you see a beautiful woman. You go over to her and say “I'm brilliant in bed. Do you fancy spending the night with me?” That's advertising.

You see another beautiful woman, and send your friend over to her. He says “My friend is brilliant in bed. Do you fancy spending the night with him?” That's marketing.

Then a third woman approaches you. She says “I hear you're brilliant in bed. Do you fancy spending the night with me?”. That's PR....

Or rather, that's the result of good PR.....

Traditional... this version thanks to Borkowski

“Some are born great, some achieve greatness, and some hire public relations officers. ”
Daniel J. Boorstin

What are the two differences between a squirrel and a rat?
A bushy tail and good PR.

If you want a more serious perspective, the Chartered Institute of Public Relations offers this definition:

Public relations is about reputation - the result of what you do, what you say and what others say about you.

Public relations is the discipline which looks after reputation, with the aim of earning understanding and support and influencing opinion and behaviour.

It is the planned and sustained effort to establish and maintain goodwill and mutual understanding between an organisation and its publics.

And if you could do with getting some plain speak.... then try this: Jargon Buster