What is SEO Page Rank?

PageRank is the name Google has given to a formula it uses to score the relative importance of any given webpage. The higher the pagerank, the more important the page.

Popular sites such as Wikipedia and the BBC tend to have high page rank (7 or more). Brand new sites start with a pagerank of zero.

One method of improving a site's performance in Google is to increase its pagerank. It's worth noting that Google places greater emphasis on page content, and that pagerank is merely one of several factors in the struggle for SEO supremacy.

PageRank tends to be earned via external links into a site from a third party site.

A link from a page with high PageRank will convey more link juice than one from a site with low PageRank. This is why SEO professionals work hard to build the PageRank of sites under their direct control. And why they pursue backlinks from sites with high PageRank.

Of course, an inbound link will work even better in terms of Google performance for a particular keyword if its contextual.

And finally, please remember that PageRank isn't the only factor Google uses to determine where your site is displayed in its results pages. It's not wise or useful to focuss on it to the exclusion of all else.