Page Rank is a Google invented metric, made to describe the relevance, or strength, of a given page within a Google index. Page rank ranges from 0 to 10 with 10 being best.
Page rank is mainly gained by incoming links. Whenever a source is credited (linked to), its Page Rank rises, and the amount depends on the PR of a page giving the link ( google patented algorithm ).
In Google's eyes, higher ranked pages are more relevant for the topic they are ranking for, and as such are more likely to appear in the search results for the same topic. And good search engine results of course mean more visitors to your site, more clients for your business.
You can observe page rank with a browser add-on (check Firefox 3 Add-ons) or with free Google toolbar .
Page Rank Sculpting
Page rank flows from one page to another, with inbound links to the page adding to PR and outbound links 'leaking' it. By structuring the links on your pages, you can have influence on how the PR is spread on your site. This is called Page Rank Sculpting.
Here is one example. I want to give most importance to my posts and pages and less to the home page, archives and categories. Reason is that the home page content is usually not constant (for a usual blog at least) as articles come and go. So I would have hard time trying to rank that page for all my targeted keyword phrases. It is much more effective if I focus my efforts to specific posts each targeting one desired keyword. So what I want is my single pages receiving most of the page rank so they would rank higher for their specific topics.
You can bulk check your current page rank (multiple pages at once) using this free tool.
How is Page Rank Sculpting Achieved?
Most commonly used technique for page rank scuplting is using nofollow attribute with the links.
Here is a quote from Matt Cutts, Google employee:
"The nofollow attribute is just a mechanism that gives webmasters the ability to modify Page Rank flow at link-level granularity. Plenty of other mechanisms would also work (e.g. a link through a page that is robot.txt'ed out), but nofollow on individual links is simpler for some folks to use. There's no stigma to using nofollow, even on your own internal links; for Google, nofollow'ed links are dropped out of our link graph; we don't even use such links for discovery. By the way, the nofollow meta tag does that same thing, but at a page level."
Official Google SEO guide also endorses usage of nofollow. They mention it in example of blog comments:
If your site has a blog with public commenting turned on, links within those comments could pass your reputation to pages that you may not be comfortable vouching for. Blog comment areas on pages are highly susceptible to comment spam. Nofollowing these user added links ensures that you're not giving your page's hard-earned reputation to a spammy site.
You want to put nofollow attribute to links to those pages that are not important on your blog, especially if those links appear on most of your pages (like header, footer and sidebar placed links). In practical terms, it can be links to Home, About, Contact, Guestbook pages then archives, categories, social bookmarking, RSS feed and similar low relevance pages.
Here is an example of a nofollowed link in HTML:
<a rel="nofollow" href="http://www.prelovac.com/vladimir/about">About</a>
Use Pages for Important Information
Another way of page rank sculpting on a WordPress blog is having important content as pages instead of posts.
For most WordPress themes, 'pages' are listed in the sidebar meaning every your post will pass it's PR to these pages. This can be further tweaked, for example you can also add links to your relevant posts to the sidebar, by using widgets for example.
SEO Siloing with Categories and Tags
Another popular 'seo sculpting' technique is called SEO siloing. It is called this way because you are 'stuffing' one page with links coming from a lot of other pages.
Best example is naming a category after keywords you want to rank for, and then create a static category landing page that contains an article and also acts like a mini sitemap for all posts in that category. With all posts linking back to this page it gets a lot of Page Rank.
There is a handy WordPress plugin for SEO siliong available here.
SEO Silioing can also be used effectively with tags. Choose your tags wisely and avoid short one-word tags. When you are tagging an article try to think of a phrase someone would actually type in the search engine when they are searching about your topic.
Taking this technique to the next level involves creating a dedicated page that will only list your most important tags (20-30 for example). Advantage of this is that this page will be linked to from all pages of your site, meaning it will have considerable page rank on it's own. It will then pass this page rank to your most important tags, in addition to all other PR they are getting from posts that have these tags.
Controlling Page Rank with Comment Sculpting
I am not sure anyone used this term before so here is what I call Comment sculpting. Since page rank is achieved by getting inbound links and lost with outbound links, if one could automatically control these links they could influence the strength of the page.
Blogs have a feature that makes it easy to implement this kind of control and that is comments. Each comment usually has a date of the comment which serves as a link to the same page. With the increasing number of comments the number of outbound links is nullified by many inbound links coming from the comments.
So a page without any comments would equally spread it's incoming page rank to let's say 20 links in your header, sidebar and footer. But if that page has 50 comments, the effects of losing page rank will be much less because 50 of 70 links take the page rank back to the same page. This means that the pages with more comments have the potential to keep the incoming page rank better. Downside of this is that these comments may also take away some of the page relevance (depends on what comments are specifically if they are of 'nice post!' sort) so having a balance between page relevance and keeping PR is important. I found that 10 per page usually works well (you would need to implement comment paging with a plugin).
Hot Tip - Google Site Search
Part of the page rank sculpting effort is knowing which pages to promote. And what better signal can you get than the one from the users visiting your site. If you have a search box available, chance is it being used by visitors. Have you ever checked what they are searching for? If not you have been missing this important metric.
If you are using Google Analytics to track visitors to your site (and you should cause it's extra easy to setup and use) you can use a feature called Google Site Search.
It will work on a WordPress blog and allows you to have information about what did users coming to your site type in the search box (almost every WordPress theme has a search box).
Setting it up is super easy. Go to your main screen of Google Analytics, click Edit settings for the site you want to enable it. Then select Do Track Site Search and enter 's' as Query Parameter. See the picture below.
You can then monitor are visitors searching for on your site, or what they expect to find. This can be also a hint of the information that is not clearly accessible so you may want to rearrange links in your sidebar for example.
Page rank sculpting can be most powerful technique in your SEO arsenal when used properly. It's form of an art, take the chisel in your hands and sculpt your website into a beautiful SEO creation.
I enjoy working on WordPress SEO and Website Optimization. If you need such services, contact me for a chat!