Understanding PageRank

Posted on February 16, 2012


A key idea to understand is Google’s PageRank, especially when it comes to understanding the effect of links in SEO.

PageRank is the backbone of Google’s search engine system, and it was what put the original Google search engine on the map. Using a combination of algorithms, PageRank measures the “importance” of a website, assigning a numerical weighting for each site that is considered during  search.

So how does PageRank do this? Google puts it simply by saying that PageRank is “a technology that determines the ‘importance’ of a webpage by looking at what other pages link to it.”

There you have it, plain and simple — linking.

True, PageRank itself specifically applies to Google, but it is still essential to understanding SEO because 1) Google is the predominant search engine used by Internet users, and 2) Google’s PageRank system changed the search engine results game, and other search engines have been modeled after it.

As we learned earlier, Google threw a major curve ball in the sport of search engines when it introduced the emphasis of in-bound linking, and therefore looking at the overall relevance of a website, rather than purely looking at content.

Wikipedia has a great breakdown of the algorithms behind PageRank, but I don’t have the brainpower and coffee supply to learn and explain it all (but definitely check it out if you do!). But there are big takeaways that mathematically challenged journalists can still take away just by looking at the surface functions of PageRank.

We need to keep in mind that, according to PageRank, not all websites — and therefore links — are created equal. The picture above is from Google’s patent of PageRank from 2010, which shows that PageRank weights how much significance is given to each link. In other words, Google will be more impressed if you get linked to by the New York Times than if you got linked to by this blog.

So when you ask a prominent blogger to give you a shout out on his/her site, you’ll not only be attracting more potential readers, your PageRank, and therefore your site’s search optimization, will increase.

Also, not only does PageRank put more stock in getting linked to by a more “important” site, it will basically completely ignore links from what it considers to be “non-important,” which is noteworthy with the prevalence of spam websites today. Consider that before dolling out countless links all over meaningless message boards. Google won’t notice or care.

From here, read my next post, which breaks down some 10 important tid-bits about links and how PageRank views them.

Further reading: Check out this interesting article about applying PageRank technology to molecule interaction.