The Google PageRank system: why PageRank is important and how to perfect it.
Posted on | February 3, 2007 | No Comments
Ah, so much confusion about such a tiny little number: PR3. Or PR5 or PR8 if you should be so lucky.
When the Google technology known as the PageRank system was created and then installed on its free toolbar, it opened up quite a can of worms. Because, predictably enough, website owners began equated their PageRank with their search engine rankings… a mistake that can lead to all sorts of misunderstandings and sleepless nights.
So let’s look at what PageRank is and what it isn’t. According to some search commentators, it’s an evil device that never should have seen the light of day. Others say it’s an invaluable tool to measure the success of a website’s link building strategy. The truth, as usual, lies somewhere in between.
What PageRank Does
PageRank, according to Google, is a system for ranking the importance of pages on a scale of zero to ten. It measures not just the sheer number of links coming into a page, but also the relative value of the pages they come from. The more important Google deems a page, the more valuable it considers any links coming from it. Merit by association.
So when conducting a search, Google uses the PageRank number along with dozens of other factors, such as keywords in content, to deliver search results that are, in their words, “both important and relevant to your search.”
The point to be gleaned from all this is that PageRank is just one element in a very complex system that Google uses when determining how high your site appears in the search results for any given term. PageRank influences your SERPs (Search Engine Results Pages) but so do a whole lot of other factors. However, because PageRank is right there on the toolbar and in your face, it’s hard to ignore and easy to understand why so many webmasters / site managers consider it the holy grail of search success, perhaps giving it more weight than it deserves.
Perfecting this One Element: The Google PageRank System
Okay, so PageRank is just one element in a very complex system and there are a whole lot of other factors to worry about. I get it. You get it. But you have to start somewhere, right?
How do we perfect the PageRank element?
To do perfect the Google PageRank System, we need to understand how PageRank is calculated. Unfortunately for us, that is a secret Google guards very closely. All we have to go by is the original paper Google published on the PageRank system. And while Google surely is using some newer variation of this calculation, it still forms the foundation PageRank and is therefore worth understanding.
The Google PageRank Calculation:
PR(A) = (1-d) + d(PR(t1)/C(t1) + … + PR(tn)/C(tn))
Simple, right? Okay, maybe it needs a bit of explanation. What we are calculating here is the PageRank (PR) of Website A using these variables:
- (t1) – (tn) are pages linking to page A
- C is the number of outbound links that a page has; and
- d stands for ‘damping factor’, which is usually set to 0.85.
Therefore, we can simplify the equation a little bit:
Page A’s PageRank = 0.15 + 0.85 * (the sum of each page’s PageRank that links to A divided by the number of outbound links on each page)
What Can We Learn From The PageRank Calculation?
1. Building In-Bound Links:
The ideal site you would like to have linking to yours has two crucial characteristics:
- High PageRank; and
- No Outbound links save for your own.
The above calculation proves quite simply that a link from a page with PR5 and 4 outbound links is worth much more than a link from a page with PR7 and 80 outbound links. The PageRank of a page that links to yours is important but the number of links on that page is also important. The more links there are on a page, the less PageRank value your page will receive from it.
2. Building Internal Links:
If you are lucky enough to have a page with high PageRank, you can use it to boost the PageRank of other pages on your site. Just remember to reduce the number of internal and outbound links on that page so that it can “lend” the most PageRank to your other page. One way to reduce your internal links on any page is reduce your main navigation through categorization. If you have several pages on one topic, create a topic page that can link to these other pages and have only the main topic page exist on your main nav.
3. Building Outbound Links:
Outbound links do not drain a page’s PageRank. However, as mentioned above, it does reduce the amount of PageRank that it can “lend” to other pages. Therefore, you should create a single links / resources page that contains all of your outbound links.
An Imperfect Toolbar?
Okay, so we’ve talked PageRank. Great. Unfortunately it isn’t the only Google toolbar feature to cause webmaster confusion. The toolbar also includes an option that displays “backward links”. When clicked, it shows you a listing that one might assume includes all sites that link back to the page on display.
One would be wrong.
All it gives you is a smattering of incoming links. So if you have spent several months or years populating the world wide web with hundreds of links to your site, a mere dozen or two might show up in this list.
To see what I mean, test one of your pages using the Google toolbar “backwards links” button, then check the same page at AllTheWeb or Yahoo!, by putting {link:} without the brackets in front of your URL. Both engines will reveal all those missing links to your site still floating around out there.
Why doesn’t Google recognize or display them? Presumably because only certain links originate from pages considered “important” enough by Google.
The Google Dance
Every so often, Google likes to add to the confusion by updating their algorithms and tossing everything we thought we knew about PageRank on its ear. So, for example, the site that had a comfy PR6 when it went to bed last night could have a PR3 hangover this morning – no warning, no explanation.
This happens because Google has either changed the way it measures the value of links, or it has made its standards for PageRank harder to attain… raised the bar, as they say. It does so to foil the unscrupulous link building efforts of those who purchase hundreds or thousands of links all at once, without earning them.
But even those who tread on the good side of the law can still get caught when suddenly the rules change. For example, not long ago run-of-site links were perfectly acceptable until one day Google decided this method of link building was just too easy. So the tactic was nixed and PageRank scores could be heard crashing all over the world.
So should you get all hot under the collar over PageRank? We recommend you pat this unpredictable little statistic on the head and get on with the more important business of building up the number of relevant, unpaid links coming from high quality sites to yours.
PageRank success will come and go, the little green bar on your Google toolbar will do the Hokey Pokey, but a solid linking strategy will see you through all the fluctuations.
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