Domain Authority is a proprietary score created by Moz that attempts to predict a website's ranking strength on a 1–100 scale. It's calculated using factors like the number of linking root domains, total backlinks, and the authority of those linking sites. A site with DA 30 is weaker than one with DA 60, but the scale is logarithmic, so jumping from 20 to 30 is easier than 70 to 80. Google does not use Domain Authority in its ranking algorithm. DA is a third-party metric built by analyzing Moz's own link index, which is smaller than Google's. That said, DA correlates with rankings because both reflect similar underlying factors: quality backlinks from diverse, authoritative domains. If your DA is climbing, it usually means you're building links that matter. Other tools have their own versions. Ahrefs uses Domain Rating (DR), Semrush has Authority Score, and Majestic tracks Trust Flow and Citation Flow. Each uses a different dataset and formula, so a site might be DA 45 but DR 52. None of these scores are perfect predictors, but they're useful for comparative analysis when evaluating link opportunities or competitor strength. At Ottawa SEO, we don't chase DA for its own sake. We focus on acquiring links from topically relevant sites with real traffic and editorial standards, regardless of whether they're DA 35 or DA 65. A contextual link from a DA 28 Canadian industry blog often outperforms a sidebar link from a DA 50 generic directory. That said, DA is a quick shorthand when vetting prospects in our 500+ domain portfolio or prioritizing outreach targets. Watch out for DA manipulation. Some sites artificially inflate their score with PBN links or link schemes, so always cross-check with organic traffic estimates in Ahrefs or Semrush. A DA 40 site with zero monthly visitors is a red flag. Use DA as one signal among many, not the final word on a domain's value.