Domain authority

Domain authority is a score out of a hundred that estimates how strong a website’s link profile is. It was invented by Moz, and the other tool companies now sell their own versions under different names. It is genuinely useful for one narrow job and it is used for a dozen others, which is why it causes more confusion than almost any other term in this dictionary.

In short

• It is a tool company’s estimate, not a Google measurement.
• Google has said plainly that it does not use the score the tools sell you.
• Every tool gives a different number for the same site.
• It can be raised by buying links, which tells you what it is worth.

Where the number comes from

Every one of these scores is calculated the same way. A company crawls as much of the web as it can afford to, records which sites link to which, and turns that into a figure comparing your link profile to everybody else’s it has seen.

Three things follow from that, and all three get forgotten. The score describes links and nothing else, so it knows nothing about your content, your speed, your reviews or whether anybody buys from you. It depends entirely on how much of the web that company happened to crawl, so a different crawl produces a different answer.

And it is scored on a curve. The number compares you against everybody else the tool has seen, which means your score can fall while your site is unchanged, simply because the rest of the web got busier. A figure that drops without anything happening is not measuring your site.

Why Google does not use it

This is not a matter of opinion or interpretation. Google has addressed it directly and more than once, and the answer has not changed: the domain authority scores sold by SEO tools play no part in crawling, indexing or ranking.

That should be less surprising than it is. Google has its own view of the web, built from its own crawl, which is enormously larger than any tool company’s. It has no reason to consult somebody else’s estimate of a site it can see directly.

Whether Google keeps site-level signals of its own is a separate question, and one nobody outside Google can answer. What is certain is that the number in your report is not one of them, and that no agency has access to whatever is.

The names, which are all the same idea

• Domain Authority, from Moz. The original, and the reason the phrase exists at all.
• Domain Rating, from Ahrefs. Different crawl, different scale behaviour, same underlying concept.
• Authority Score, from Semrush, which folds in some traffic estimation alongside links.

None of them are comparable with each other. A site scoring sixty in one tool and forty in another has not changed. Two companies looked at different portions of the web and reached different conclusions.

What it is actually good for

There is a real use, and it is narrower than the way the number gets deployed.

As a rough comparison between two sites in the same field, checked on the same day with the same tool, it tells you something. Is this potential link source substantially better connected than that one? Are we in the same rough band as the competitors we keep losing to, or an order of magnitude behind? Those are reasonable questions and the score gives a reasonable first answer.

What it cannot do is tell you whether you deserve to rank for a particular search. Ranking happens page by page, against a specific query, and a site-wide average has very little to say about that.

The ways it gets misused

Four patterns account for most of the damage.

• Reported as a result. A score that rose during a campaign is presented as evidence the campaign worked, when it usually means somebody acquired links.
• Used as a link filter. Turning down a relevant local link because a tool scored the site poorly is a genuine loss for a genuinely poor reason.
• Sold as a target. Agencies quoting a score to reach are selling movement in a number they can influence directly, which is not the same as selling customers.
• Treated as a grade. Businesses conclude they cannot compete because a number is low, when the pages they need to rank face far less competition than the site-wide figure implies.

The number you can buy

The strongest argument against relying on it is that it responds to exactly the thing it should be resistant to.

Because the score is built from links, buying links raises it. A site can purchase its way to a respectable figure in months while ranking for nothing at all, and this is common enough that it has its own small industry. Any measure that improves when you spend money on the practice it is meant to detect is not measuring quality.

Google’s own systems discount those links, which is why the score and the rankings can point in opposite directions for the same site. When they disagree, the rankings are the ones describing reality.

What to report on instead

Replace one invented number with three real ones.

Which of your pages earn search impressions and clicks is the first one, because that is Google telling you directly what it makes of each page rather than a tool guessing at your site. How many inquiries arrive through search is the second, and it is the only number the business itself cares about. The count of separate sites linking to you is the third, and it is the honest version of what the score was estimating all along, which is why it belongs on the backlink entry rather than here.

All three come from tools you already have. None can be purchased. And none of them require anybody to explain what a score out of a hundred is supposed to mean.