Neobot's Weblogs: The Concept of Google PageRank

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The Concept of Google PageRank

PageRank is a numeric value that represents how important a page is on the web. According to Google, PageRank relies on the uniquely democratic nature of the web by using its vast link structure as an indicator of an individual page’s value. In essence, Google interprets a link from page A to page B as a vote, by page A, for page B. But, Google looks at more than the sheer volume of votes, or links a page receives; it also analyzes the page that casts the vote. Votes cast by pages that are themselves “important” weigh more heavily and help to make other pages “important.” Hence, Google calculates a page’s importance from the votes cast for it, and considers the importance for each of these votes when it calculates a page’s PageRank.

How is Google PR Calculated?

To calculate the PageRank for a page, all the incoming or inbound links to that page are taken into account. These links could be from within the website or from other websites. The equation to calculate a page’s PR is given below.

PR(A) = (1-d) + d(PR(t1)/C(t1) + … + PR(tn)/C(tn))

A is the page whose PR is being calculated.
t1 - tn are the pages which are linking to the webpage A
C is the number of outbound links on that page
d is a damping factor and its default value is 0.85

The value for ‘d’ varies and Google also uses other variations of the formula given above.

A simpler version of the formula can be:

Page’s PR = 0.15 + 0.85 * (a share of the PageRank of every page that links to it)

Since Google PR is equally divided among the outbound links of a page, the share of PR passed to every site is

( PR of page t1 / Outbound links of page t1 ) * ( % of the amount of PR to be passed)

Hence, the % value is taken as 0.85 since a page ‘votes’ an amount of PageRank onto each page that it links to, which is shared equally among all the pages that it links to.

From this formula, we can see that a link from a page with PR 5 with 10 outbound links is worth more than a link from a page with PR 8 with 100 outbound links.

5/10 = 0.5 whereas 8/100 = 0.08

When searching for link partners, the PageRank of a page of the linking site should be taken into consideration as well as the number of outbound links on that page. The more outbound links a webpage has, the less PR value will be passed to your webpage.

PageRank or PR is important as it is one of the factors that determine a page’s ranking in Google’s Search Results. Of course PR is not the only factor that Google uses to rank pages, but it is important.

Google and Inbound Links

Every Search Engine has its own policies and guidelines which it follows in order to determine the link popularity of a website. Google is stricter in its policy of counting incoming links to a website. Usually, Google will disregard any incoming links placed on pages with Duplicate content, pages in Supplemental Results, or pages with lots of unrelated links etc. Also, Google will disregard any links coming to a webpage from banned websites. These policies change over time, and the real algorithms and policies are never made public by the Search Engines.

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