Domain Authority (DA) is a proprietary score developed by Moz that predicts how likely a website is to rank in search engine results pages, expressed on a scale from 1 to 100. The higher the score, the greater the predicted ranking potential of that domain.
It is important to understand that Domain Authority is a third-party metric created and maintained by Moz. It is not a signal used by Google, nor does it factor into Google's ranking algorithm in any way. Confusing DA with an official Google metric is a common misconception. Google has its own internal link-based signal, historically known as PageRank, which is not publicly available in the same way. Domain Authority exists as a practical proxy that SEO professionals use to estimate a site's competitive strength based on observable data.
Moz calculates the DA score primarily by analyzing the quantity and quality of backlinks pointing to a domain. A backlink is a hyperlink from one website to another, and links from authoritative, well-established sites carry significantly more weight than links from obscure or low-quality sources. The score also incorporates the total number of linking root domains, meaning that receiving links from many distinct websites is more valuable than receiving many links from a single source.
Because Domain Authority uses a logarithmic scale, improving a score from 10 to 20 is considerably easier than improving it from 60 to 70. This means that gains become progressively harder to achieve as a site's authority grows, and small fluctuations at higher score ranges are normal and expected.
A closely related metric is Domain Rating (DR), offered by Moz's competitor Ahrefs. While both scores aim to measure the strength of a domain's backlink profile, they are calculated using different methodologies and data sets, so the two numbers are not directly comparable. SEO professionals often consult both metrics alongside other signals when evaluating a site's authority.
In practice, DA is widely used for competitive analysis, link prospecting, and evaluating potential content partnerships. When assessing whether a site is worth pursuing for a backlink, a higher DA score generally suggests a more authoritative source. However, DA should always be interpreted in context. A score of 30 may be highly competitive in a niche industry while being modest in a broader market. Relying on DA as a standalone measure of site quality can be misleading, and it is most useful when compared against direct competitors rather than treated as an absolute benchmark.