SEO for Google Part II: Google PageRank Algorithm
The PageRank formula is proprietary to Google and it is a method by which Google calculates authority for a given page on the Internet. It is commonly referred to as PR or by its numeric value PR0 thru PR9, the higher being the more authoritative. In other words, a PR0 site is an “unknown” and a PR9 site (there are very few of them, Google is one) is the top of the totem pole. Many people mistakenly believe that PageRank is site specific – completely false – it’s all in the name. Your home page may carry a PR4 but every other page on your site may be a PR0. This is an important concept to grasp as it dictates your linking strategies and site wide architectural design.
When trying to conceptualize PageRank, think of it as water that flows from one site to another. If you have higher value pages pointing to you, you have PageRank flowing to you. Likewise if your site is filled with outbound links pointing to other websites you are essentially telling Google that you are irrelevant because you send all of your traffic somewhere else. So, like water, you can have “leaks” wherein PageRank is leaking out of your site and going to someone else. This is a pretty important concept to understand as it will have definitive impact on your site performance.
The algorithm itself is, of course, completely classified – no one outside of Google truly knows exactly what defines PageRank and likely very few inside of Google know either. Interestingly enough, Google does not hold the patent to the trademark PageRank – it is held by Stanford University which has issued Google exclusive licensing rights for the mere sum of $336 million dollars back in 2005. Standford University also acquired 1.8 million shares of Google stock in the transaction.
This is the way that Google themselves describe PageRank: “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’.” While quite vague, that is about as much detail as you’re likely to hear from Google on the subject.
There are general facts that we do know, however, and other information that has been gleaned through observation and testing. PageRank is not merely assigned based on number of links, for example – it is far more complicated. The number of incoming links is one of more than 100 claimed influences on PageRank. The quality of those incoming links (authority of the site they came from) also plays a major role in PageRank, as do numerous other factors such as the age of the domain, and even things that you might think irrelevant such as when your domain registration expires. Google looks at a company that purchases their domain registration and prepays for 5 years in advance as a much more stable and trustworthy company than one that just purchases it year to year. Fundamentally, PageRank is a combination of trust, relevance and authority and it is distributed based upon traffic flow and linking structures.
Looking at the numbers you find that PageRank varies from PR0 to PR9 – PR9 being the rarest of the rare and the highest rank available. But don’t get discouraged as you are trying to climb up the PageRank hill that things are moving very quickly. Indeed, it does take a while and it appears that Google only periodically updates PageRank because when it does change, it seems to change for several things at once. Also, it is import to note that the PageRank scale is not linear. A PR1 is not twice as good or doesn’t have twice as many links as a PR0 – it just doesn’t follow that type of linearity. It is logarithmic in nature; meaning that the higher you get the harder it is to move up. Getting to a PR3 is not that difficult, but moving up from there begins to be quite arduous.
PageRank can be manipulated or, to some extent, controlled via a bunch of different approaches – everything from stopping up the leaks (areas on your site where PageRank is flowing out from the site), to not allowing its distribution (via NOFOLLOW attributes on links), to simply designing an intelligent linking structure to enhance your sites page rank through bringing in one way links of higher value to your strategic pages. This becomes crucial as you try to climb up the SERPs (search engine results pages) and achieve higher rankings while competing with other higher PR sites.
In some regards PageRank is important, but in many others it is not. The bottom line is that PageRank may or may not have anything to do with your earnings from your business. The reason for that is that PageRank is not necessarily related to traffic and many sites chose not even to worry about PageRank and instead focus on other metrics that govern their bottom line. It seems that in the past several months to a year, PageRank has somewhat become depreciated in the SEO marketplace as being less important that initially thought to be. In the end it is important to have a core understanding of it and try to design your site in a way that maximizes your PageRank, but it is only one piece of a successful website and should not be your primary goal or concern. In fact, the intent is that it is naturally obtained anyway, though, through SEO we manage to influence it. Keep your priorities in line and focus on revenue and in your SEO efforts be cognizant of PageRank and how to help it along, but don’t dwell on it.