The Background of PageRank

Google's PageRank (PR) is one of the most sought after, and yet misunderstood, web page attributes. PageRank, named after one of the founders of the Google search engine, Larry Page, was the innovative foundation that the Google search engine was built on.

The theory was that a link from one web page to a web page of another site was in essence a vote for that page. The reasoning was that webmasters would only link to pages that they thought were interesting and of value to their viewers. Google used the number of inbound links (IBL) to a page to judge the importance and relevance of that page, and based on this calculation, and other factors, decided where to place that page on the search engine results page (SERP).

They devised a scale of measurement for PageRank from 1 to 10. Then for the information of webmasters and interested people they produced a toolbar that can be deployed in Internet Explorer that will indicate the PageRank value of any page being viewed in the browser. These values have become known as PR0 to PR10. Note: A reader has pointed out an apparent contradiction between a scale of 1 to 10 and a reporting of PR0 to PR10. In fact PR0 indicates no PageRank. One cannot be said to have PageRank until the site achieves a PR1 ranking.

Since PR values are a result of IBLs, Google decided to give them their own name and refers to inbound links as backlinks. As part of the toolbar there is a quick lookup of the number of backlinks that Google reports for the page that is currently being viewed in the browser. This search can also be done without the aid of the toolbar by simply typing "link:http://www.yourURL.com" into the Google search box.

The one trick to this link search is that Google does not display all backlinks. At one time it was thought that they only listed pages with a value of PR4 or greater. Today however, you will find backlinks reported from pages of lower PR values. So, at best, Google's backlink search seems to present some sample of  pages linking to the site. Suffice it to say that this search is not a reliable measure of all IBLs to a page.