Friday, 22 August 2008

Google's PageRank

One of the most heated debates in the SEO sector can be generated by Google's PageRank and specifically the green PageRank indicator on the Google Toolbar - is this really a useful indicator of how Google's views each web page, or should it be completely ignored as a distraction? The question is also raised as to what purpose this indicator serves for most web users and why Google even bothers to display this.

Google's trademarked 'PageRank' algorithm and underlying technology is one of the main foundations of the search engine developed by Sergey Brin and Larry Page and was also a core factor that enabled Google's search results quality to stand out from existing search engines when it first launched in the late 1990's. Google's own corporate pages describe PageRank as follows:

PageRank reflects our view of the importance of web pages by considering more than 500 million variables and 2 billion terms. Pages that we believe are important pages receive a higher PageRank and are more likely to appear at the top of the search results. PageRank also considers the importance of each page that casts a vote, as votes from some pages are considered to have greater value, thus giving the linked page greater value. We have always taken a pragmatic approach to help improve search quality and create useful products, and our technology uses the collective intelligence of the web to determine a page's importance.

The underlying PageRank algorithm is a complex mathematical formula, which is then simplified by the short indicator bar on the Google Toolbar, where the green colour filling the bar indicates the PageRank 'score' between 0/10 and 10/10. New sites will start with a completely grey bar with no score and then develop a higher PageRank as the site gets indexed and starts attracting links from other domains.

The PageRank score on the Toolbar is a snapshot and an occasionally updated figure - Google's Matt Cutts recently alerted people in his blog that a new update was being posted and back in 2006 had provided more information about the Toolbar indicator with answers to some readers' questions. It's clear that it would be wrong to place too much emphasis on this Toolbar figure for each website and web page, but it's also short-sighted to dismiss it completely when it does provide some degree of information from Google's perspective.

So the Google Toolbar shouldn't be a figure of primary concern but a useful indicator of relative performance and potential development. It does give website marketers a view of their own and competitors web pages and how pages within a site hold different PageRank scores. It shouldn't be a core driver of an SEO strategy but perhaps confirmation of how the search marketing support for a site is developing its potential performance on Google.

There's an excellent article on Google PageRank provided by Search Engine Land.

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