PageRank is a proprietary technology used by Google to “score” a page importance
A few very clever people have written about what PageRank (Google PR) is and how it works, and there probably isn’t anything groundbreaking that I could add to the discussion (see the last paragraph of this post for link to some very good articles on Google PageRank).
Having said that, a lot of webmasters (even experienced ones) are still confused about PageRank, what it is and what impact it has on their website. Hopefully this should clear a few misconceptions that may still live in their mind.
PageRank is… : 8 things to know
- PageRank in its current form is constantly re-calculated and re-adjusted, it is referred to as “live” or “internal” PR. The PageRank that you can check using the above tools is called “Toolbar” PageRank (even if you are using a widget/website) and is a snapshot at some point in the past. The “little green bar” is also a common way to refer to Toolbar PageRank as it is represented by… a little green bar
- PageRank is awarded on a page by page basis not a site basis, even if it gets “passed” from one page to another;
- PageRank is a logarithmic scale: it is easier to get from 0 to 1 than it is to get from 1 to 2 and so on. I tend to use the following image to illustrate the PageRank scale to people new to the SEO sphere. It is a good representation of the “efforts” required to climb up the scale – or mountain in that case:
(src. Elliance PageRank explained. Please note: do not rely on the name opposite the PR figures, this infographic dates back from 2008)
- PageRank is based on links – and only links – and scores a page “popularity” or “importance”. Each link from a page A to a page B equates to a “vote” from page A to page B (and the “voting” only goes that way). However:
- Not all votes carry the same “weight”:
- All things being equal, a vote from a popular page in itself will carry more weight than one from a non popular page;
- All things being equal, a link from a page that has a fewer links, will carry more weight than a page that has more;
- Some links might not carry any “weight” at all:
- If the website owner used the rel=” nofollow” attribute on the link;
- Not all votes carry the same “weight”:
- PageRank is only one – very small – ingredient (ranking factor) in the complex recipe that Google uses to rank websites (algorithm). The algorithm is not only complex, with allegedly over 200 ranking factor, but its also a fiercely guarded secret, so it hard to know exactly what part PageRank plays in it – if any at all.
- PageRank can be “manipulated” (called PageRank sculpting or PageRank hoarding) or even faked, be aware of these possibilities if you are only looking at PageRank as a measure of quality (which you SHOULD NOT do);
- Lastly, PageRank gets its name from one of the founder of Google (Larry Page), if you really wanted to know.
PageRank isn’t… : 5 more things to know
- A web page with a high PageRank is not guaranteed to rank highly in Google for the keywords targeted by that page – the context of the links and “theme” of the pages doing the linking plays a greater role in Google’s algorithm than the “simple” mathematical value of a link;
- Based on the above, a web page with a low Google PR pages can rank higher than ones with a higher value, for many resons;
- Based on the above two points a website with a high PageRank can have fewer visitors than one with a lower PageRank: ie. high PageRank is not a guarantee of a high number of visitors;
- Although it is very common for a website homepage to be awarded the highest PageRank of a website (links are usually pointing to it), it is possible for an internal page to have a higher PageRank, especially on new sites / blogs;
- Two pages with the same PageRank might not be equal: PageRank is a decimal point value, so a PR4 might could mean PR4.01 or PR4.99. To know if you PageRank is on the “strong” side (closer to the upper number than lower), check you website homepage PR value, and compare it with the pages 1 level deep: if you see the same PageRank on internal pages and your homepage, it – roughly – means you should soon move up a notch.
So what is the use of PageRank then?
- Depth of crawl: how far down your website will the Google search engine bots/crawlers will go to find content;
- Supplemental results: the supplemental index is a “secondary” index where pages that are not “popular” are stored (although this is an entirely new subject in itself);
- Frequency of crawl: there are rumours that PageRank also has an impact on how often the crawlers will come to a site to get content, but I would suggest that regularly upaded content or adding new pages, will have a stronger impact on crawl frequency.
- Google dangles PageRank in front of webmasters and uses it as a massive carrot to keep them focussed on an issue that has long lost its importance;
Want to know more about PageRank?
Then you should read the comprehensive pieces from Danny Sullivan (What is Google PageRank?) and Vitaly Friedman (Google PageRank: What do we know about it). Both article date back from 2007, but are still relevant today (even if the PageRank importance as a ranking factor is questionable).
And if you REALLY want to know more about PageRank, from a technical point of view, check out the two articles at the end of Danny’s already in-depth blog post: Phil Craven Google PageRank explained and Ian Rogers Google PageRank algorithm and how it works and this one from David Austin How Google finds your needle in the web’s haystack.