Domain Authority is a Moz-invented score (0–100) that predicts how well a site might rank. Google doesn't use it, doesn't see it, and has repeatedly confirmed it plays no role in their algorithms. DA is a third-party metric based on Moz's crawl data and link analysis, similar to Ahrefs' Domain Rating or Semrush's Authority Score. These are useful for comparative analysis when evaluating link prospects or competitor landscapes, but they're not ranking factors. Google uses its own authority signals, many of which remain proprietary. Historical PageRank concepts still influence how link equity flows through the web, and Google evaluates signals like link quality, topical relevance, user engagement, and content quality. A site can have high DA but rank poorly if its content is thin or off-topic. Conversely, niche sites with DA under 30 often outrank DA 60+ competitors when they nail search intent and earn relevant links. At Ottawa SEO, we track DA as one diagnostic tool among many. When auditing a 500+ domain portfolio, DA helps quickly flag which properties have stronger backlink profiles or might pass more equity in internal link networks. It's a rough proxy for link authority, but we never optimize for DA directly. We optimize for Google's actual signals: earning links from relevant, trusted sources in the client's niche, improving content quality, and building topical authority clusters. The practical takeaway: don't chase DA for its own sake. A link from a DA 45 industry blog often outperforms a DA 70 general news site if the former is topically relevant and the latter is a random guest post. Focus on link relevance, editorial standards, and traffic potential. DA is a convenient shorthand when comparing link opportunities, but it's a correlation metric, not a causation lever. Google's algorithm is far more nuanced, weighing hundreds of signals DA can't capture.