Thursday, June 3, 2010

How Google Ranks Pages


Google uses a sophisticated and proprietary algorithm for ranking Web sites that uses over 100 different criteria in the calculation, each of which is given a specific weighting which can change over time. Because the algorithm can change, specific techniques that used to work well may no longer work as well over time. This is important to remember when your site’s ranking seems to change for no apparent reason. For this reason, optimizing your site should not be considered as a one-time task. You should always try, test, and refine your efforts.

The Google algorithm can be broken down into two major groups of factors:

On-page (keyword) factors. Keyword factors involve how, where and when keywords are used. Meaning how well your website is optimized for your most important keywords, and if those same keywords appear in your content and in links. Keyword factors determine page relevance.

Off-page (link) factors. These include the quantity and quality of links that point to your site. Link factors determine page importance and are related to Google PageRank (PR). Links play a VERY important role in getting high rankings, particularly for competitive markets.

Very simply put, Google finds pages in its index that are both relevant and important to a search for a particular term or phrase, and then lists them in descending order on search results pages.

On-Page Factors and Page Relevance

Keywords are intrinsically related to search terms – words and phrases that people enter into a search engine to find specific information. Most people enter 2 to 5-word phrases in Google to find what they are looking for. Google in turn analyzes all pages in its index and lists the pages which contain those search terms. Each web page usually contains one or two keywords that are repeated more often than others throughout the site. These keywords dictate the “theme” of a website.

In addition, Google analyzes other sites that contain links to your site. Specifically, Google looks to see if the text of a link (the clickable portion) that points to your site also contain those same keywords.

Off-Page Factors and Page Importance

Page importance is all about links - their quantity, quality, and strength, which we will discuss later on. This part of the algorithm includes Google PageRank (PR).

Google looks for links that point to your site from other websites. Google believes a link from website A to website B is a “vote” for the importance of website B. In this way, other websites add votes for your website, which in turn helps increase a pages PageRank value on your site. Each page on your site has a PR value. Usually the PR value is the highest for the home page as most people will link to your home page rather than another page on your site.

The more web pages that link to your site, and the more important in turn those pages are, the more important Google thinks your site is and hence the higher your PageRank value. Moreover, it is the quality, as well as the quantity, of links that matter – not all links are valued the same. Keep in mind that PageRank is but a single (albeit important) factor used in ranking.

Sites that are highly optimized for on-page factors can outrank sites that are less optimized but have higher PageRank. PageRank value is assigned after comparing every page in the Google index against one another. This is billions and billions of web pages. Note that PageRank does NOT factor in keywords or phrases used on your site.


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