SEO External Ranking Factors PageRank

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Google PageRank - Theoretical Basics

PageRank is one of the most known link analysis algorithms used by the Google search engine. Google uses multiple methods of determining the ranking of a listed web page, PageRank remains the most important one, being the basis of Google's system. The Google developers, Larry Page and Sergey Brin, developed it before they put the basis of the Google search engine.

Google was the first search engine to take into consideration inbound links when deciding which are the most important web pages to display. Each of the pages listed by Google are estimated separately and each of them is given a certain PageRank (Google assigns a numeric value ranging from 0 to 10 for each webpage on the Internet, showing the importance of that web page for the Google search engine).

One of the main purposes behind PageRank is to find criteria to determine the importance of a certain web page. In order to do this, Google takes into consideration the possible frequency visits to that web site. Google tried to determine a web pages importance by taking into account a behavior very close to the real way of browsing the Internet. A normal person would start from a certain web site (it is a random page, its address is of no importance here). From this page, the user will go to other sites by following the links present on the first site he had visited. While he or she may visit other sites by following these links, it is also true that he may not follow any link after all, and start viewing another random page. When developing PageRank, Google specialists estimated that this latter probability is 0.15 at each step. The following 0.85 is the probability that the user will visit other web pages by following the links on the first site, assuming all links are equal in this case. In the probability that the user will continue visiting web sites indefinitely by jumping from link to link, the logic outcome is that popular pages will get more views than not so popular web sites. This probability that a user may visit that web page is behind that page's PageRank (the sum of both probabilities, 0.15 + 0.85 is 1, because the user is assumed to be visiting at least one Internet page at any given moment).

Google uses certain mathematical equations to transform these probabilities into numbers, because working with probabilities is not always a convenient thing to and because whole numbers are easier to understand. Google's PageRank uses numbers from 0 to 10 o rank a web page. When a certain web page first appears and it has no links towards it, it has a rank of zero, because the chance for a person to find it is very small. Each web page that has links to other sites shares with them its PageRank, so the PageRank of each of the outbound link is inversely proportional to the number of links (the more links a site has, the lower will be the PageRank allocated to each of the links).

The total distributed page rank is reduced by 15% (representing the above-mentioned probability that a user will not continue following any of the links). You should know that the above-described PageRank algorithm of web page ranking is not used in its pure form. Instead, Google has developed it and combined it with other methods a well. In the following segment, we will discuss the practical use of Google's PageRank.

Using PageRank alone is not always a very efficient method of ranking web pages, because it ignores the text of links and the information on that linked page. Current estimates are that Google ranks pages according to thematic PageRank (it also takes into consideration the value of links coming from other similar thematic pages). Google ToolBar is a method through which you can determine the PageRank value of any web site listed by the search engine. You should known that ToolBar will not show you the page's probability value according to PageRank, but rather PageRank range that site is in.

PageRank has two main practical uses. First of all, it is used to quickly check a site's popularity. However, it will only give you the feel of the page's popularity. You can use PageRank's results to find out, for example, if your search engine optimization process has proven efficient. If a site has a PageRank between 4 and 5, it is an average popular web page. A higher PageRank value of 6 or 7 means that your web page is extremely popular, while the highest possible ranks, of 8, 9 or 10, are granted to very large and important corporate web pages (such as Microsoft, for example). If you are offered by another site a request to exchange links, you can also resort to Google's PageRank to find out the importance and value of the link given in exchange. By comparing the quality of the pages in the requested exchange is similar in value to the pages already existing on your site, the exchange is profitable.

You can also use PageRank to make an impression about the sites' value in any specific query. For example, you can use it to see among all the pages displayed when a search is performed the PageRanks of six or seven. If the site you are using to compare it against the others is awarded a PageRank of 4, you can be sure the latter will not be displayed among the first displayed results. Another thing you should remember is that Google ToolBar only updates its PageRank results once every few months, so the information you are looking at right now can be somehow outdated.

Because the basic PageRank evaluation system can be vulnerable to certain types of manipulation to obtain an artificially better-ranked web page, Google has continuously tried to improve it and the methods of evaluating the importance of web sites.