PR is a measure of "important" is a page (according to Google). For the purposes of this article, I'll just talk about public relations in the context SEO - what it means and how to use it.

First things first: PR is not the cause or the result of high rankings.

PR depends mainly on two things: inbound links and traffic. Some SEO make the mistake of assuming a high ranking comes as a result of the high band, when in fact high PR is a natural result of a high ranking.

Best SEO higher score = more traffic = more PR

However, the concept behind Google's PR is crucial when working with external links (ie input) and internal links (ie the structure of the website). Each link from A to B is considered a "vote of confidence / credibility" from A to B. We may use public relations as a physical measure of how this credibility travels from one URL to another.

The role of SEO in this case is ...

    Outside facilities: to maximize the incoming PR increasing the number of incoming links and quality inbound links.
    On site: to leverage PR input, so that none of this is lost (in broken links) and most of it is channeled to the most important pages of the website (ie: web page, category pages principal)

In short, PR is not a factor in SEO is not a direct result of the SEO. However, the characteristics of a high PR site are very similar to those of a high ranking website. And because of that, the concept of public relations can be used to ...

    properly apply the techniques of linkage
    measure the effectiveness of these techniques