Domain authority (DA) is one of the most common metrics in search engine optimization (SEO). Every major SEO tool, from Moz to Ahrefs to Semrush, has some way to measure domain authority. New websites — early-stage startups, for example — typically have fairly low domain authority. Large, legacy websites — like Wikipedia, for example — have high domain authority.
In short, a website’s domain authority is determined by the number of backlinks to the site and the strength or quality of those backlinks. Building backlinks will increase your site’s domain authority and help it rank better in organic search.
In this post, we’ll break down what domain authority is, how it works, and how you can improve it to boost your site’s search engine rankings.
Google’s PageRank and the History of Domain Authority
The concept of domain authority first appeared in Moz, an SEO tool. It’s the “strength” of a domain or, more specifically, the relevance of a website (at the domain level) on a given subject.
Before Google, search engines worked by counting the number of times relevant keywords appeared on websites. This method returned low-quality results because websites could easily game the system by repeating specific keywords.
Google added a new layer to search quality by using both the keywords on a page and how often other websites linked to that page to determine the page’s relevance. Each link meant that someone thought the page was useful enough to share. Links from reputable sources were also given more weight. This formula was called PageRank.
In Google’s early days, they released a toolbar that web developers could use to check a website’s PageRank score. It gave developers a good idea of how well their site would rank in comparison with competitors so that they could optimize their sites accordingly. Perhaps predictably, people kept trying to game the system. Black hat link-building schemes became commonplace, and the quality of search results suffered.
In 2016, after battling against manipulators for more than a decade, Google decided to remove the publicly available PageRank tool.
Without the PageRank tool, developers could only roughly predict the strength of their sites’ authority. Various SEO companies jumped in to fill the gap with products that served the same function, such as Semrush’s Authority Score and Ahrefs’ Authority Checker.
Among them was Moz, and its Domain Authority standard. While domain authority tools, including Moz’s, are not determinative — that is, Google does not reference them when determining page ranking — they do give website developers a close approximation of how search engines like Google will treat a particular site across a variety of search terms.
How Does Domain Authority Work?
Generally, the higher a website’s DA score is, the better it’ll rank across keywords in a search engine like Google.
For example, Wikipedia has a DA score of 98 out of 100, while Forbes has a slightly lower score of 95. For most searches, Wikipedia will rank higher than Forbes. But on the subject of business, Forbes might win in rankings by being a more specialized, relevant source.
Like a PageRank score, a DA score is an assessment of a site’s quality, which is indicated by the number and quality of its backlinks. This is also known as link equity.
Assessing Link Quality
Not all links are treated the same. Google considers the nature and strength of the backlinks to a particular site or domain.
Domain authority considers the authority of the linking site when determining scores or how much link equity is passing to a website. If Wikipedia and its mighty 98 DA score link to your site with a dofollow link, that link is worth more than a similarly relevant link from a site with a score of 50, and much, much more than a site with a bad reputation and a correspondingly low score or authority.
While the relevance of the backlinks you build may not directly impact the DA score your site gets from a tool like Moz, it’s also very important. At ContainIQ, we wrote an article about Kubernetes that was linked to by a Kubernetes-centric newsletter. This was great in terms of increasing our site’s relevance to that particular subject. If the same article were linked to by a newsletter about iced tea or some other unrelated subject, Google would significantly discount the value of the link.
Assessing Link Quantity
Once the quality of each link is determined, domain authority looks at something much simpler: the sheer quantity of links to your site. All things being equal, a site with more quality links will rank higher in search than a site with fewer quality links.
In other words, the more backlinks a website has pointing to it, the higher its domain authority will be.
Understanding Page Authority
Like domain authority, page authority is a metric used by Moz to predict how well a specific page will rank in organic search. Page authority differs from domain authority in that it focuses on the page level.
As you build backlinks to specific pages on your website, those pages will increase in page authority, and your entire website will also increase in domain authority.
To get an idea of how this works, imagine a website selling computer hardware that published a viral blog post on keyboards. If that post got dozens of quality backlinks from keyboard-focused websites, Google might very well consider that page to be more of an authority on keyboards than it considers the domain in general to be. That difference is what page authority tries to measure.
How Content Does — and Doesn’t — Matter
A common misconception regarding domain authority is that your score can be improved by having either more content or better content. Domain authority doesn’t measure how good the writing on your website is, so that isn’t a part of how your score is arrived at — at least directly.
That being said, more and better content indirectly affects domain authority. Having content on more subjects gives other sites something to link to, and making sure the content is good makes them want to link to it.
Improving Domain Authority Score & Using it Effectively
If you need to improve your site’s DA score, there are a few steps you can take.
Building Backlinks
We’ve said it several times in several different ways, but to be absolutely clear, we’ll say it again: Domain authority scores go up when your site has more quality backlinks.
This isn’t the only factor, but it’s one of the biggest factors and one of the factors directly in your control. We’ve written in detail about the different ways you can go about building quality backlinks, but the CliffsNotes version is something like this:
- Write Data-Driven Content: People love to link to stories built on interesting, novel or counterintuitive data. A very successful article that gets widely shared can result in hundreds of quality backlinks.
- Write Guest Blog Posts or Contribute Content: This is one of the oldest and best strategies. If you know of a site you’d love a link from, figure out the kind of content they like to post and pitch them. It’s a win-win — they get free, high-quality content, and you get the exact kind of backlink you need. You can also control the placement and anchor text of the included links.
- Get Included in Resource Pages: These are the generic, bulleted resource pages you see on websites everywhere. Many companies maintain lists of helpful links on various subjects. Go find these pages on relevant sites — for example, schools or colleges — and write content that would be beneficial to them. Then email the site and ask them to include the link.
- Create Link-Bait Resources: Writing informational articles that are linked to is both an art and a science and an easy way to semi-passively build links over time. Both 26 Kubernetes Statistics to Reference and How 8 Giant Companies Use Kubernetes & 60 Others That Use It were written with this goal in mind and have accumulated a large number of links between them over the years.
Using Internal Links to Distribute Authority
Internal linking, linking from one page in a domain to another in the same domain, allows you to spread your link equity from more successful pages to newer pages that need help. If you have a page about keyboards with high page authority, an easy improvement is to strategically link to other relevant internal pages. Internal links can be used to redirect or distribute authority from pages on your website to other pages that you’d like to rank higher.
As a bonus, internal links also help your website visitors navigate from pages they’re interested in to other pages on the same topic in an organic, helpful way.
However, while internal links are great for distributing page authority, they do not directly impact domain authority.
Avoiding Link Penalties
Relevant search results are Google’s primary product, and it does everything it can to make sure that that’s what its users get. Trying to game the system by buying links or employing other shady practices often results in Google penalizing your website through manual actions or algorithmically harming your rankings.
Even if you’ve always tried to follow the rules, following best practices can be a hard and complex task. It’s possible to have backlinks that lower the quality of your website’s reputation and never know, which is why tools like Semrush’s Backlink Audit exist. These tools analyze your site’s backlinks and highlight low-quality links that might be lowering your domain’s reputation, so you can address them, return to compliance, and improve your results.
Using Topical Authority to Overtake Sites with More Domain Authority
Earlier, we mentioned how Forbes, with a DA score of 95, can sometimes outrank Wikipedia, with a DA score of 98. That happens because Google believes that Forbes is a better source for business content than Wikipedia. This is also known as topical authority or relevance.
At ContainIQ, we built a library of more than 200 articles, all on Kubernetes. In Google’s eyes, we were one of the top sources of information for Kubernetes. As a result, we could beat sites with higher DA scores than ContainIQ when it came to Kubernetes-specific keywords.
Domain Authority at Work
The image above is taken from Moz’s free domain authority checker, and it shows the results for IMDB.com, the internet’s most popular movie database. People know and trust IMDB, but more importantly, people talk about the data IMDB offers: they use it to settle arguments and to help one another remember the names of obscure actors, and they often link back to IMDB when they do so.
Given the massive number of backlinks IMDB gets, it’s not surprising that they have a very high DA score of 95. When you look up a movie or director, Google sees IMDB’s massive collection of organic, legitimate backlinks and, as a result, prioritizes IMDB’s pages over those of thousands of other, lower authority sites. For example, IMDB typically ranks above a similar website, Rotten Tomatoes, which has a domain authority of 92.
The links under the Page/URL heading on the left are a perfect illustration of how distributing page authority with internal links works. The five links take you to pages with information on five specific films:
- Avatar
- Inception
- The Dark Knight Rises
- The Matrix
- Back to the Future
Are these the best five movies ever made? That’s debatable, but it’s also not relevant. IMDB is using its domain authority, and page authority, to redistribute link equity to other pages on its website that they’d like to rank higher — and that’s helpful for readers, too. It’s a win-win.
Final Thoughts
At a high level, domain authority is dead simple. It’s a prediction of how the biggest search engines in the world will judge the quality of your site.
There’s no easy way to “cheat the process.” The best way to increase your DA score and show up higher on Google’s results page is to make a good-faith effort to give them what they want. Creating relevant content and using it to build backlinks will raise your DA score, and creating content relevant to specific topics (and getting it linked to by high-authority sites specializing in the same subject) will increase your individual page authority and topical authority, which will, in turn, help you to overpower sites with higher DA scores.
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