Glossary
What is Domain Authority (and Similar Third-Party Metrics)?
Domain Authority is a third-party metric (originally developed by Moz) that scores a website's likely ranking strength on a 1–100 scale based on its backlink profile — it is not a metric Google itself publishes or uses directly in ranking.
Several SEO tool vendors (Moz's Domain Authority, Ahrefs' Domain Rating, Semrush's Authority Score) publish their own version of this kind of score, each calculated with a different proprietary formula, mostly based on backlink quantity and quality. They're useful as a relative, directional comparison between sites within the same tool — a domain scoring 60 is generally stronger than one scoring 20 in that same tool — but they are estimates of ranking potential, not a number Google itself calculates, consults, or exposes.
The common mistake is treating one of these scores as a direct ranking factor to optimize toward, or comparing a score from one vendor's tool against a score from a different vendor's tool as if they were the same scale — they aren't, since each company calculates it differently.
A more reliable signal of real authority is a site's actual organic performance in Google Search Console — impressions, clicks, and average position for real queries — which reflects Google's actual ranking behavior rather than a third-party tool's estimate of it.