Well to preface, Google provides a quality score or an “importance level” for each page of a website that it indexes. These quality scores can be found buy either downloading the Google Toolbar for Microsoft IE or by installing a plugin like SEO Quake for firefox. Google Chrome also has some great SEO plugins you can install that will also display a webpage PR once visited.
Google PR or PageRank is primarily based on how many quality relevant links you have from other sites to yours. Each website linking to yours is classified as a “vote” for popularity that directly impacts your PageRank once Google does its PR updates (usually 3 or 4 times a year).
The algorithm these days for PR however is not simply calculated by the number of backlinks. reciprocal links (exchanging links), affiliate links, low PR links all score relatively low as “not important” links. Links from relevant sites with High Pagerank (these days PR4 or greater) will benefit immensely as “important links”.
A simplified explaination of pagerank and it’s original creation is:
Imagine there are 4 websites in google (A,B,C and D. Each one would start with a PR1 once indexed by Google.
If website A,B and C each link to D and D is not linking back to them then D would score a PR value of 4 and would show up on top of the search results for the phrases it was optimized for. If A,B,C and D are all cross linking to each other, their PR would most likely still be the same and only the well optimized site for certain keyword phrases would show up in the search results top spot. (this is explained in much simpler terms in my program).
Written by Mark Stoffels