Domain authority

Domain authority is a third-party score — most recognizably Moz's "Domain Authority" metric — that predicts, on a logarithmic 1–100 scale, how well a domain is likely to perform in search results, based largely on the size and quality of its backlink profile. It is important to note this is not a metric Google itself publishes or uses; it is a modeled estimate built by an SEO tool vendor from crawled link data.

Other vendors publish similarly purposed but differently calculated scores — Ahrefs' Domain Rating and Semrush's Authority Score are the best known — and because each uses its own index and formula, scores from different tools are not directly comparable; a domain scoring 40 in one tool will not necessarily score 40 in another. Google has stated publicly that it does not use any third-party domain authority metric as a ranking factor in its own algorithm.

Domain authority is useful as a rough, consistent-within-one-tool benchmark for competitive research, comparing how link-worthy a domain looks relative to competitors, or prioritizing outreach targets during keyword research and content planning aimed at growing organic traffic, rather than as something to directly optimize for. The recurring pitfall is treating a rising DA score as proof of improving search engine results page rankings, or comparing DA, DR and Authority Score figures across tools as if they sat on one shared scale, when each is a distinct, vendor-specific model with its own methodology.