How Google Distributes PageRank

In the SEO realm there is a lot of focus on PageRank as an indicator of a domain's worth. Although it is probably one of the most important factors in a domain's worth in the eyes of Google, there are a few points that should be mentioned.nnPages that don't have any PageRank are often symbolised as having N/A PageRank.Google gives each page on the web a weight and when one web page links to another it passes some score onto the page it is linking to. The higher the PageRank, the more likely Google is to trust it. This is true for both external and internal links. Google PageRank has eleven values, between 1 and 10. First of all, 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. nnProbably the most important factor in the distribution of PageRank to a web page is the PageRank of the pages linking to it. The higher the PageRank of pages linking to a given page, the higher its PageRank is likely to be. PageRank is generally not assigned to a web page higher than the pages that link to it. So, if a page has 4 PageRank 4 and 3 PageRank 3 links pointing at it, it will probably be give a PageRank of 4. In addition, web pages that have a lot of low PageRank and PageRank N/A links pointing to them can have their PageRank reduced as a result. Sheer quantity of links does not help to increase PageRank. A website can have a high PageRank with relatively few links pointing to it if those links are of a high PageRank.nnThere are those that suggest that the text content of a page affects PageRank assignment, but this doesn't seem to be the case. There is no substantiated evidence that text affects PageRank other than pages that have been spammed often have their PageRank removed.nnWhen it come to sub-pages, time is a factor in PageRank distribution. When new sites first get given PageRank their sub-pages often remain without any PageRank. In general, sub-pages are a little slow to get assigned 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 really struggle to pass their PageRank to internal pages.nnThe architecture of the site has a major role to play in the distribution of PageRank. Google uses what is known as block level analysis to pick apart web pages. They use their knowledge of the structure of the web to decide what links on a page are probably the most trustworthy and the pages these links point to are more likely to receive PageRank.nnGoogle can and do change websites' PageRank. This is generally as a penalty for sites that have used unhonest practices. 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 distribution.nnLastly, the PageRank of a web page may change even when there has been no change in the links pointing to that page. This is either due to changes in the structure of links between all websites or modifications made by Google.nn