If you’re into SEO then by definition you need to understand Google’s PageRank.  PageRank along with several other factors is used to determine the ranking of a page within Google’s index.

What is Google PageRank?

PageRank is an algorithm that assigns a numerical weighting to a web page in Google’s index. It was developed by Google’s founders Larry Page and Sergey Brin while at Stanford University in 1998 to help determine a page’s importance relative to other pages on the web.

Google describes it as:

PageRank relies on the uniquely democratic nature of the web by using its vast link structure as an indicator of an individual page’s value. In essence, Google interprets a link from page A to page B as a vote, by page A, for page B. But, Google looks at more than the sheer volume of votes, or links a page receives; it also analyzes the page that casts the vote. Votes cast by pages that are themselves “important” weigh more heavily and help to make other pages “important”.

So what is the PageRank algorithm?

It is defined in the original paper published by Sergey Brin and Lawrence Page as:

We assume page A has pages T1…Tn which point to it (i.e., are citations). The parameter d is a damping factor which can be set between 0 and 1. We usually set d to 0.85. There are more details about d in the next section. Also C(A) is defined as the number of links going
out of page A. The PageRank of a page A is given as follows:

PR(A) = (1-d) + d (PR(T1)/C(T1) + … + PR(Tn)/C(Tn))

Note that the PageRanks form a probability distribution over web pages, so the sum of all web pages’ PageRanks will be one.

You’ll find a lot more detail about PageRank on Wikipedia or you can read the original paper which you’ll find here.

What is the PageRank of my site?

You can find the PageRank of you site using the Google Toolbar or using the tools such as this. It is widely believed that the Google Toolbar PR is not updated as often as the PR values that Google uses in it’s rankings, this seems to be part of Google’s attempts to stop the practice of selling links for their PageRank value.

Does my PageRank influence my position in Google Search results?

Yes, PageRank was devised to help Google rank sites in the Search Engine Ranking Pages (SERPs). However it is only one part of the equation, the content of your site and how it is structured and the anchor text used to link to your site also affect the ranking.

When does PageRank gets updated?

Google is believed to update their PageRank regularly however the results shown on the toolbar are updated far less regularly, typically it seems to be every 3 to 4 months at the moment.

How can I predicted the PR of a web page?

You can use tools such as the PageRank Predictor. Although the results are only an estimation of your likely PageRank.

What I can do to increase my PageRank before the update?

Find sites related to your content and ask for incoming links from relevant pages. Ideally you want to get incoming links from pages with as high a PageRank as possible, but any and all links will help. The best links will come from sites with a high PageRank themselves that chose to link to you on the basis that you are relevant to their visitors. You’ll get the best links by having content that is worth linking to.