Dynamic nofollow for fine siloing
Having a clear web structure and make the search engines perfectly understand it is one the things I believe as fundamental for a good SEO.
I wrote about the multi categories website structure issue as a first step but let's go ahead playing a bit with nofollow technique, PageRank sculpting and siloing concepts.
Two quotes in one to start
Nofollow attribute is a mechanism that gives the ability to modify PageRank flow at link-level granularity, said Matt Cutts
and point it in the very best directions, added Rand Fishkin
UPDATE/NOTE: Few weeks after I wrote this article there was the 'nofollow burst' but I decided to let the noise pass by without changing a coma. Recently SEOMOZ's Danny Dover tested nofollow still working for PageRank sculpting. I don't want to buy any of both ideas, just testing myself in several sites. I'll write about when some clear conclusions achieved.
PageRank sculpting is about the right way to use the nofollow attribute at internal link structure to let the PageRank flow the under control the way you want so a nice way to make your content structure crystal clear as mentioned before.
Anyhow, a wrong nofollow policy can hurt your rankings but Rand explained few days ago the Dangers of Nofollow. First check the video for better understanding what we are talking about.
Internal link structure
A quick look at any regular web site will draw the typical structure: home, categories (navigation menu), content under categories and what we'll call service pages as contact page, about, sitemap, legal advice and so.
At any page in any level there are links to the rest of categories through the menu and the service pages. This creates a complex net of internal linking without any order of relevance. The consequences are what we are hardly trying to avoid:
- A very confusing content structure for search engines
- Vertical hierarchy of content or siloing idea disappear completely
The solution here is use nofollow but in a dynamic website things change from page to page and we need some code to distribute nofollow attributes as required or it won't work as desired.
Somehow the page where you are in a certain moment has to know where it is placed inside the general sitemap and code should apply nofollow to some of the links depending on the circumstances of that page.
As I code my own sites it is easy to me implement this technique but for those using Wordpress quite sure there must be a plugin doing something similar. Anybody knows about?
Some diagrams to explain it better.
Home page level links
Basically at home level you want to keep all the paths free of obstacles so all of them are followed.

Links at categories level
Here we start applying some rules:
- Service pages are nofollowed, about, contact, sitemap for example
- Links to the rest of categories are nofollowed
- Links to content pages under the actual category are followed
This will keep some verticality at structure strengthening and preserving theme siloing.

Content level links
Again:
- Service pages are nofollowed
- Links to other categories but the actual one are nofollowed

Some more rules
- If there are subcategories same concept must be applied
- Link to home is always followed to keep linkjuice circulating internally from bottom to top
- If there is a logo leading users to home page and a text link doing the same always nofollow one of them.
- External links: do follow the ones adding value to content, nofollow the rest.
Live example of dynamic nofollowing for a perfect siloing
In the case you need a live example of this dynamic nofollowing idea, please, install the Nofollow display Greasemonkey script for Firefox and navigate this blog taking a look at top right links and menu ones. You will see it in action.
Any thought you would like to share?
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