What is Domain Authority (DA)?
Moz’s 1–100 prediction of a domain’s ranking strength, driven largely by links. A third-party proxy, not a Google metric: use it for triage, never as a goal.
Related terms
Domain Rating (DR)
Ahrefs’ 0–100 measure of a site’s backlink strength. Like all third-party scores it approximates authority; it does not confer topical relevance.
Topical Authority
The depth and breadth of expertise a site demonstrates on a subject, earned by comprehensively covering a topic and interlinking it rather than publishing scattered pages. Engines reward the site that most completely owns a subject with rankings across many related queries.
URL Rating (UR)
Ahrefs’ page-level link-strength score. Useful for comparing two competing URLs’ backlink weight, not for judging topical fit or content quality.
Off-Page SEO
Everything that builds a site’s reputation elsewhere: backlinks, mentions, reviews, and digital PR. Off-page signals validate what on-page content claims about expertise.
Referring Domain
A unique site linking to you. Domain diversity matters more than raw link counts: 100 links from one site look like one relationship, not 100 votes.
Link Equity
The ranking value passed through a link, shaped by the source’s authority, relevance, and number of outbound links. Internal links distribute equity; external links earn it.