This lesson will explain how Google applies different weights to backlinks and how you can measure the quality of links in your link building campaign.
Why is the Quality of Backlinks Important?
As covered in our earlier lesson on link building, backlinks are one of the most important ranking factors in SEO, however not all links are treated equally.
Rather than just calculate the quantity of links pointing to a webpage, Google also takes into account the authority, relevance, position and editorial nature of those links.
The most important thing when analyzing link prospects is that bad links can hurt your SEO. SEO is meant to be a natural, organic process and Google penalizes websites that violate their Webmaster Guidelines with paid, manipulated or low quality links. You can use the processes on this page in order to avoid accidentally building low quality or spammy links to your site.
Methods that Google Uses to Measures the Authority of Links:
1. Domain Authority, Page Authority and Toolbar Page Rank
The most important factor for determining the quality of the link is the link authority of the website’s homepage and linking page.
As covered in our article describing how Page Rank works, the Page Rank model is based on link equity and link flow. The higher the authority of the website’s homepage and linking page, the more valuable the link.
The easiest way to calculate the authority of the homepage and linking page is by using Moz.com’s OpenSiteExplorer.org tool, which shows the respective Domain Authority (DA) and Page Authority (PA), scored out of 100, for a given URL. The higher both of these numbers are, the more valuable the link is. As you can see below, SEOBook.com has a DA of 84 and a PA of 86 (very high).
Example of the OpenSiteExplorer.org Backlink Checker Tool with DA and PA Metrics
MajesticSEO.com has another tool called “Trust Flow” and “Citation Flow”, which also aims to measure the link authority of a URL. The former is based on the number of “trusted” domains pointing to the website while the latter is based on the number of citations to the brand’s homepage. Essentially, the higher both of these numbers, the more valuable a link from that site will be. Personally, I prefer to use the DA/PA metrics above rather then Majestic’s, however they can both be used together for greater accuracy.
Finally, many SEO agencies also use the Page Rank Toolbar to calculate the authority of a webpage when ascertaining the value of a link from it. However, Toolbar Page Rank has become increasingly unreliable in the last 2 years and less frequently updated.
2. Relevance of the Website or Article
In addition to measuring the authority of websites, Google must also be able to understand the relevance and topical nature of a specific website or page. This is because as part of the search process, Google must not only deliver high quality results but also relevant results for the user’s query.
One of the primary methods Google uses to understand the topical relevance of a webpage is through its backlinks and the anchor text of those backlinks. Getting backlinks from relevant websites or pages that closely match the subject your website will help a lot in ranking for your keywords.
For example, if you run a dog training website that has links from other dog training websites, blogs and pet owners, then this would be more valuable than links from off-topic articles such as football news, sports and economic affairs.
3. Overall Look, Brand Signals, UX and Content Quality of the Website
While link authority is still very important in SEO, Google has got much better at analyzing the on-page quality of a website, which includes its design, content quality, brand signals and overall user experience.
In fact, all of these factors made up parts of the Panda algorithm, which was rolled into Google’s core search algorithm in 2013. This illustrates just how important Google views all of these factors in SEO.
As such, when deciding whether you want to receive a link from a site, you should scrutinize the overall quality of the site’s content, whether they have strong brand and social signals, and the overall look and feel of the site. If it’s high quality with excellent content, it’s likely to be a very valuable site to receive a link from.
In contrast, if the content is low quality, spun content or lacking in value, you should think twice about getting a link from that site.
4. Editorial Nature, Comments and Freshness of a Page
Following on from the above, Google has also began to add more weight to pages or articles with greater editorial control or that are updated more frequently.
This is because pages that are updated more frequently are likely to have greater editorial control and value, which is what backlinks were originally designed to measure.
Pages that regularly receive new links or comments help to keep the page fresh (as Google sees that the content of the page changes), therefore links from such pages will be more valuable.
5. Prominence and Position of your Link on the Page
Google’s original Page Rank algorithm was designed to attribute weighting to backlinks in order to rank websites. As part of this formula, links that were higher up the page and more likely to be clicked would pass more link value than the others.
In the following video, although Matt Cutts (head of Google’s Search Team) explains that the order of links on a page isn’t important for SEO, he also backtracks on this statement by saying he wouldn’t make the most important link the 1001th on the page.
We also now know that if you have two links pointing to the same URL on a webpage, Google will only “count” the anchor text of the first link on the page.
In January 2014, Matt Cutts also warned SEOs against the practice of guest blogging. This could mean that backlinks in the author profile at the bottom of a page may pass even less value than before, as predicted by this article 12 months earlier.
6. The Number of Outbound Links on a Page
The Page Rank algorithm works by calculating the link authority and link equity of a specific webpage. This can informally be called “link flow”. The more external links you have on a page, the more diluted the link flow becomes and the less weight will be passed through your link.
Therefore, backlinks from pages with fewer external links will pass more authority than pages with dozens or 100s of external links (e.g. directories).