Page rank is a system developed by Google to provide an indication of the quality of individual Web pages. Page rank is an algorithms used by Google to determine relevant, high-quality search results.
Google Page Rank (PR) is a number value from 0 to 10. Google page rank is calculated on periodic basis by Google for each and every specific page in Google index. Google PR is page specific not site. The PR of you website vary from page to page.
Page rank ranks each web page on a scale from 1 to 10. Page rank is determined by the number of inbound links that a page has from other relevant, well-ranked Web pages. Each inbound link acts as a 'vote' concerning the quality of the page and helps to improve its page rank status.
The page rank of any Web page can be checked using the Google toolbar application.
How does Page Rank work?
Google Page Rank for a particular page is directly proportional to the number of links that point to it. However, these links are not all given the same weight. Google claims that some links are more important because they originate on pages that are themselves considered important. So, out of two links from two different pages, a link coming from a page with a higher Page Rank will be given more weight in the algorithm. Besides being dependent on Page Rank of the originating page, the weight of a link is also inversely proportional to the number of links originating from the same page. That is, a link coming from a page with 20 other links on it will be given much less weight than the link coming from a page with only 2 links.
That means that it is possible for a page with only one backlink to have a higher Page Rank than a page with multiple backlinks, if this link originates from an “important” page with few links.
On top of these factors, in determining link weight Google also takes into consideration whether or not the linking page is in the same domain or on the same server, geographical proximity, text within the anchor text and immediately surrounding it, and originating page content.
The PageRank Algorithm:
The original PageRank algorithm was described by Lawrence Page and Sergey Brin in several publications. It is given by
PR(A) = (1-d) + d (PR(T1)/C(T1) + ... + PR(Tn)/C(Tn))
» PR(A) is the PageRank of page A,
» PR(Ti) is the PageRank of pages Ti which link to page A,
» C(Ti) is the number of outbound links on page Ti and
» d is a damping factor which can be set between 0 and 1.
So, first of all, we see that PageRank does not rank web sites as a whole, but is determined for each page individually. Further, the PageRank of page A is recursively defined by the PageRanks of those pages which link to page A.
The PageRank of pages Ti which link to page A does not influence the PageRank of page A uniformly. Within the PageRank algorithm, the PageRank of a page T is always weighted by the number of outbound links C(T) on page T. This means that the more outbound links a page T has, the less will page A benefit from a link to it on page T.
The weighted PageRank of pages Ti is then added up. The outcome of this is that an additional inbound link for page A will always increase page A's PageRank.
Finally, the sum of the weighted PageRanks of all pages Ti is multiplied with a damping factor d which can be set between 0 and 1. Thereby, the extend of PageRank benefit for a page by another page linking to it is reduced.