How Google Decides PageRank
Date Added: March 17, 2009
Author: Jessica Navarro
In the SEO community there is a lot of attention paid to PageRank as an indicator of a domain’s SEO value. Although it is one of the most important factors in a domain’s worth in the eyes of Google, there are a few points that should be understood.
PageRank is generally not assigned to a page higher than the pages that link to it. Sheer quantity of links does not help to increase PageRank. It should be noted, pages that have a lot of low PageRank and PageRank N/A hyperlinks pointing to them can have their PageRank reduced as a result. So, if a web page has 4 PageRank 4 and 3 PageRank 3 links pointing at it, it will probably be give a PageRank of 4. A website can have a high PageRank with relatively few links pointing to it if those links are of a high PageRank.The higher the PageRank of web pages linking to a given page, the higher its PageRank is likely to be. The most important factor in the assignment of PageRank to a web page is the PageRank of the pages linking to it.
This is true for both external and internal links. Google PageRank has 11 scores, between 1 and 10. Google gives each page on the web a weight and when one web page links to another it passes some value onto the page it is linking to. To begin with, for anybody who doesn’t know what PageRank is – it is a score used by Google to decide how important a domain is based on analysis of hyperlinks. Web pages that don’t have any PageRank are often notes as having N/A PageRank.The higher the PageRank, the more likely Google is to trust it.
Some suggest that the text content of the page affects PageRank assignment, but this doesn’t seem to be the case. There is no evidence that text affects PageRank other than pages that have been spammed often have their PageRank removed.
When it come to sub-pages, the time Google has known about them is a factor in PageRank distribution. When new sites first get assigned PageRank their sub-pages often remain without any PageRank. In general, sub-pages are a little slow to get give PageRank. Google is generally less trusting of sub-pages unless they belong to a trusted domain. In particular sites with a lot of sub-pages and even more so sites that link to a lot of internal pages (like directories) can struggle to pass their PageRank to internal pages.
The architecture of the site has a major role to play in the assignment of PageRank. Google uses what is known as block level analysis to analyses web pages. They use their vast knowledge of the structure of the web to decide what links on a page are probably the most important and the pages these links point to are more likely to be assigned PageRank.
Google can and do modify websites’ PageRank. This is generally as a penalty for sites that have used unhonest methods. This can often cause all the site’s sub-pages to loose their PageRank. It has also been claimed that in the past Google has made mistakes in PageRank updates.
Finally, the PageRank of a web page may change even though there has been no change in the hyperlinks pointing to that page. This is either due to changes in the structure of links between all websites or adjustments made by Google.