PageRank Explained

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When Google founders Sergey Brin and Larry Page first developed Google as a university project they determined that sites with the most links were probably the most trustworthy sites on the web.  They then devised a ranking algorithm called “PageRank” which analyses those links to find out which sites have the most.  The algorithm has gone through many changes since its inception around the turn of the century but at its core it is still the same.  Therefore Google, at its core, is also still the same.  In other words, the site with the most quality links tends to rank at or near the top of the search results page for searches.

How Does PageRank Work?

PageRank at its core is about assigning value to links.  As I said above, the PageRank algorithm analyzes links to find out which sites have the most.  But it also assigns a value to those links.

To understand how this works, let’s look a simple scenario involving 4 websites:

Let’s say for simplicity sake that each site only has a 1-way link to one of the other sites.  The arrows above represent that link.  So in the above example, Site A links to Site B, Site B to C, C to D and D to A.  Those are the only links.

If Googlebot finds Site A, it assigns that site a value of 1.  It then follows the link to site B and gives it a portion of the value of Site A.  Google uses what’s called a “dampening factor” to reduce the value of the link from site A to site B.  What the value is now is anyones guess, but it used to be .85.

So in the example above, the value of Site A is 1 while the value of Site B is .85.  Once it finds and follows the link from Site B to Site C and applies the same .85 dampening value, site C’s value becomes 0.72 (0.85 x 0.85).  It then follows the link from site C to site D and applies the dampening value to site C’s value of 0.72 to make it 0.61.

But now it finds the link from D to A.  Remember A started at 1.  So we apply the dampening factor to D’s value of 0.61 and it becomes 0.52 which is added to Site A’s value of 1 to make Site A’s new value 1.52.

1.52 is now used as the new value of A and Googlebot continues the cycle, following the link to B, applying the dampening value, adding that to site B’s previous value and so on.

Now I know what you are saying – if Googlebot continues like this it will get caught in a loop.  The engineers at Google have already considered this so made Googlebot smart enough to stop at some point.  So let’s say for argument sake that the number of iterations Googlebot does is equal to the number of sites in the group.  In this case Googlebot will go through 4 iterations.

If we continue the calculations we find:

As we can see, after the 4 rounds the “Final” PageRank of Site A is 3.53 while Site D gets a 2.17

Keep in mind I have over simplified this model but in essence this is how PageRank is calculated.

Toolbar PageRank versus “Real” PageRank

If you have a website you may have heard people talk about PageRank.  In fact some people can tell your sites PageRank value using various tools.

The PageRank value that Google lets us see is on a scale of 0 to 10 with 0 being the lowest value and 10 being the highest value.

But many in the industry believe the PageRank value we see isn’t the “true” PageRank that Google uses to determine the value of your website.

In fact, the values Google lets the tools use are rarely updated.  This makes it unreliable because your sites real PageRank value may be much higher or lower than the tool value.

Is PageRank Calculated on a Linear Scale?

Some people wonder if PageRank increases on a linear scale.  In other words, does it take the same number of links to increase a site’s value from 2 to 3 as it does from 7 to 8?  In other words, is PageRank represented like this?:

 

 

In fact, PageRank looks more like this:

 

 

Where it takes more to increase from a value of 7 to 8 than it does from a value of 2 to 3.

How do I Improve My Site’s PageRank?

As I said at the beginning of this article, Google at it’s core still relies on the PageRank algoritm at some point for  it’s rankings.  While other factors are also at play PageRank is still used.

Therefore it should be obvious that in order to increase your PageRank you need to increase the links to your site.

Now that doesn’t necessarily mean you need to go out and buy or build hundreds of new links.  In fact there are parts of the algorithm that discount new links if they occur to quickly.

The easiest way to start increasing your site’s PageRank is to look internally.  Look at your site structure.  Are all the pages linked to in some way?  Or are there orphaned pages somewhere on the site?

By ensuring every page contributes to the overall PageRank of your site you can improve the value.

Second, regularly add new pages.  Remember that pages have value that can get transferred to other pages.  Much like the example above with 4 sites.  Imagine that was a site with 4 pages?  What happens if you add a 5th page?  Well let’s calculate it out:

 

 

As you can see, simply adding 1 page in the simplified example increases Page A’s value to 4.34!  What could be easier than writing a new blog article or creating a new site page?

Summary

As you can see PageRank is all about links; Whether they are internal or external inbound links.  The more links your site has the better it will perform in the search engines.

There are other things PageRank does as well.  For example, I’ve found increasing the PageRank value on sites also increases the frequency and depth of Googlebot visits.

By adding new links (both internal and external) Googlebot visits my site more, and indexes more pages when it visits.  So much so that where I used to see new pages show up on Google in hours, I now see them indexed in minutes.

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