What is PageRank?
The World Wide Web is one massive pool of information, where every webpage is but a tiny drop. Search engines accomplish the amazing task of sorting out information according to relevance and popularity, making it easy for users to find what they need in an instant. There are many metrics and signals that Google uses to determine what position your webpage will get ranked for a keyword phrase, and PageRank plays an extremely important roll.
Named after Google co-founder, Larry Page, the PageRank algorithm essentially assigns webpages with numeric values in order to measure them according to importance and creditability.
According to Google:
PageRank works by counting the number and quality of links to a page to determine a rough estimate of how important the website is. The underlying assumption is that more important websites are likely to receive more links from other websites.
At a very basic level, this link analysis algorithm assigns a numerical weight to webpages, with the purpose of measuring its relative importance and credibility. The numerical weight that it assigns to any given element E is referred to as the PageRank of E and denoted by PR(E). So a PageRank of 8 is denoted as PR8. This calculated number, with the lowest score of zero and highest score of ten, is one of the important signals (out of approximately 200) that Google’s algorithm uses to determine where you will rank.
Mathematically put, the PageRank of a webpage (A) is conferred by the accumulation if its linking pages (B, C, D) PageRank’s score, divided by the number of outbound links (L).
So the PageRank value for a any page (in this case u) is dependent on the PageRank values for each page v contained in the set Bu (the set containing all pages linking to page u), divided by the number L(v) of links from page v.
This in mind, you can begin to look at links as editorial votes. When you link to a page, that link passes on a portion of editorial credit, or link juice, that will increase the PageRank of the page it is being linked to (unless the link is tagged with a NoFollow attribute). A webpage with a PageRank of 8 passes link juice of much higher value than a webpage with a PageRank of 1, as demonstrated in the below example.
Now, these algorithm and visual examples are extremely basic, and there are many other mathematical factors that play into the PageRank algorithm, such as the dampening factor, and other algorithmic elements. You can learn more about these advanced elements in these two amazing academic studies; What is in PageRank and PageRank Explained.
So there you have it, PageRank is like a popularity contest among webpages, using backlinks as votes. If you would like to know your PageRank, PRChecker is a fun tool to use, and will also give you other statistics as well, such as AlexaRank, Website Value, and more. Here are the PageRank values of some popular pages:
The NoFollow Attribute
Google recognizes that, in many situations, a site will not want to pass its PageRank to another. A common example is a site that allow users to comment, giving the site no control over their outbound links. In cases like these, sites put automated measures in place to tag these links with a NoFollow attribute. This prevents PageRank, or link juice, getting passed to the page it is linking to.
<a href=”http://www.example.com/” rel=”nofollow”>Link text</a>
It is best practices to have your site assign the NoFollow attribute in scenarios like this. Google has penalized sites that have allowed users to add links in comment boxes without the NoFollow attribute, as this is one of the most popular Black Hat methods of linkbuilding. Google provides more information about this in their documentation on NoFollow Best Practices.
So what does PageRank mean for SEO
So obviously you want links built to your site. Despite frequent algorithm updates, backlinks are still extremely important and valuable to SEO. However, avoid acquiring links through Black Hat methods.
Back in the day, people used to game the system by creating link farms, one-stop websites that were dedicated to building links to sites. Link farms are websites that were created to link back to other websites, usually a collection webpages filled with hundreds of links. They are regarded by Google as spam websites. Just as there are great pages to acquire links from with high PageRank, they are also pages that can have a negative impact. Too many links from sites that Google has tagged as spammy can potentially ruin your website trust.
Voting for a webpage that has voted for you effectively cancels out the vote. Two-way and three-way link trading practices are highly discouraged because these do not necessarily vouch for the credibility and importance of the information presented in a webpage. Link buying practices have also emerged, where people pay others to link back to their website just to increase their PageRank. Google discourages websites from participating in link buying and selling practices because these practices violate their guidelines in providing quality search results to users. Penalties include loss of trust, lower PageRank and dropped search result rankings. In the worst case, they can even result in expulsion from search results (being blacklisted) – rendering your website virtually lost in the limbo of the World Wide Web.
What Google says about PageRank
It’s interesting to know that PageRank is a trademark of Google, but the patent is assigned to Stanford University. However, Google has exclusive license rights on the patent. Stanford received 1.8 million shares of Google in exchange for use of the patent, and the shares were sold in 2005 for $336 million.
Remember, PageRank is just one of the many algorithmic metrics that influence your page’s rankings in the SERPs. The best way to increase your PageRank is to implement good SEO practices as the foundations of your website. Produce high quality content that people will want to reference. If your content is really good, it may just get linked to by a .gov or .edu domain, which are the bread and butter of backlinks.