”Internal Linking to Promote Keyword Cluster” explained the math of how strength passes internally between pages of a website and how it can be influenced with a focused and planned internal linking structure. The limitation of this approach is that it assumes that all internal links are created equal. This isn’t the case.
Several factors influence the weight and relative importance of an internal link. For example the format of that link, its position on the page, its position relative to other links, etc. While the specific way that the engines weigh individual links is not known (and would likely change even if it was), there are principles you can be apply to understand how the weight is being carried through your site past simple mathematics.
Location, Location, Location
The simplest (and arguably most effective) first step is to think like a visitor. In the desire for search engines to provide as relevant a result as possible, they work hard to emulate as best they can a visitor experience.
While the fine folks at Google (and Bing of course) can't visit every site on the web, they can create automated systems that do an excellent job at understanding how the web works, how elements are positioned on a page, and what those elements look and behave like. From this they can gather an understanding of how important a link is.
Let's look at the following basic diagram of a simple website (the dotted line indicates where the “fold” line is, everything above it is visible to the average user on first visiting the site):
The rule of thumb you can follow is this: the more visible the link is, the higher the weight it will pass. Let's look at each of the main link elements and grade them on a scale of 1 to 10:
I list the sidebar links first as I tend to use them as my baseline. Sidebars are often the spot for links you want people to be able to find easily enough but not important enough to make it to your main navigation. They are positioned above the fold, however there are usually many of them in a list, thus reducing their visibility. When I'm thinking about my weighting of links, I usually use the sidebar links as the baseline at 5 and grade the rest up-or-down from there.
This is the single most visible link area on a page. The majority of websites use the logo as a link to the homepage. The weight of this link will be high as Google knows that this link is extremely visible and highly clickable. As far as a link zone is concerned, the header is the 10 as far as potential weight passing is concerned.
Main Navigation Links
These links are highly visible and engines know that these links tend to point to the key pages on a website. This is where you as a visitor look to find product or contact information, and the engines know that. Pages linked to in this area will be given a high relative weight. This zone is given a 9 out of 10 for weighting.
We're going to discuss breadcrumb links further below as they offer more benefits than their direct position would imply however when we're looking at just position we have links that are highly visible, close to the content (and thus the eye) and clearly indicated as links. They hold a relative weight of about 7.5.
While I likely don't have to tell you that this is the least valuable link zone on your page, I will for completeness. This zone is almost always below the fold and because it tends to contain a list of links in a row, these links have low independent visibility. Finding one link in the set and predicting what links you'll find is difficult. This zone would be given a generous relative weight of 2.
In the illustration above we have included an image link. Images are difficult to determine the relative weight of in that the engines are good but not great at “seeing” an image to determine whether it is highly visible. Even still, if the graphic is bold and meant to draw the eye, you can safely assume that it will be given higher-than-average weight based on its location on the page and size. In the example above of a single image link (or on an ecommerce page with at most 20-or-so image links), the zone would be given a relative weight of 7.
These are links written into the content of a page to take a visitor to a different page on the site (in fact, you can see an example in the first paragraph of this article). These links are highly visible, provided that the visitor is reading the copy. From a pure position-on-page perspective these links would be akin to the sidebar links in their weight coming in at a 4 or 5. We'll discuss below why they're more valuable than this, however, when we consider other weight elements.
Relevancy, Relevancy, Relevancy
So far we've discussed the weight of specific zones of links based only on what the search engines can gather from their position on a page. This is far from the only consideration that needs to be made. There are many other important aspects that can increase or decrease the value of an internal link. One of the most important of these is relevancy.
Relevancy comes into play when the engines are given signals other than a link's position that enable them to add value to a link. Let's look at how relevancy is assigned to the core link zones.
Header & Main Navigation Links
The header and main navigation link zones tend to imply importance and site-wide relevancy. They are inherently highly relevant pages across the site and are rewarded appropriately by passing this relevancy on.
Sidebars can be relevant. I've seen some good sites that adjust their sidebar based on the section the visitor is in. Doing so and tying together the most relevant pages in this way can help move a bit of weight over to the sidebar links though more of the benefit will come from the math outlined in the article referenced above.
Breadcrumb links are inherently relevant. Their entire purpose for being is to help users visit pages related to the page they are on. Further, working backward through the breadcrumb links the engine can pass more relevancy to those closer to the final page.
Due to the clearly defined nature and predictable layout of breadcrumbs (Schema anyone?) the relevancy they pass is high (at least in the case of those locations close to the current page).
Very low relevancy.
By using alt and title tags you can boost the relevancy of an image, surround it with text related to the target location (easy enough with products) and you can boost the value of an image link by allowing it to pass relevancy along with its weight.
Right after breadcrumbs, content links are the easiest way to pass relevancy. The ability to surround the link with text related to the target subject and use relevant anchor text as the link is a big help in passing relevancy, but more… when you link in your content you're telling the engine that the target of your link is so relevant and important that you want your visitor to simply be able to click a link and go straight there. Basically, that what you're linking to is potentially so relevant that the visitor may want to stop what they're reading and go to the next page.
We've discussed location and relevancy, but there are other aspects of links that can add or diminish from their value. Let's take a quick recap of what we've covered and add to that a few quick additions to leave you with some takeaways.
What We've Learned:
- The location of a core link zone on the page establishes the baseline of how much weight it will pass.
- The relevancy we can establish between a link and its target page will augment the value of the link.
- As we discussed, the visibility of a link adds to its perceived value. A bold link in the content will carry more weight than a non-bolded link based on the perception that bolded text is meant to draw the eye. Use it as such, your site will look horrible if you bold every link.
- The placement of a link relative to other links impacts its weight. If the engine sees a list of 50 links in a row they can determine that the visibility of an individual page in the list is low. The relative weight passed drops with this perception as well as with the math discussed previously. I've seen main navigation areas made useless by sloughs of drop downs that obliterate the math of link-weight passing and further reduce the value of the zone by turning the links into lists hundreds long. And here's the thing, doing so makes the visitor experience onerous… and so the work of the engines is effective at keeping users from difficult websites.
Simply, when you're looking at your page, ask yourself, how easy is a link to spot and how easy is it to know why you're linking. And remember, not every link is equally important. The task then is to help the search engines know which links are the most important to help them steer the page weight to the most important internal pages.
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