Domain Authority is a search engine ranking score developed by Moz that runs from 1 to 100, with higher scores indicating greater likelihood of ranking well in search results. It's built on a machine learning model that examines dozens of factors, primarily focusing on the quantity and quality of inbound links pointing to a domain. The score is logarithmic, meaning it's much easier to jump from 20 to 30 than from 70 to 80. Google does not use Domain Authority in its algorithm. DA is purely a third-party metric created by Moz to help SEO practitioners estimate a site's competitive strength. The score updates roughly monthly and fluctuates based on both your site's link profile and the broader link graph, so your DA can drop even if you gained links simply because competitors gained more or better ones. Key components that influence DA include the number of unique referring domains, the authority of those linking sites, the total volume of backlinks, and the internal link structure. A site with 500 links from 50 domains will typically score lower than one with 500 links from 300 unique domains, because link diversity matters more than raw volume. At Ottawa SEO Inc., we track DA across our 500+ domain portfolio but never optimize for it directly. Instead, we focus on acquiring editorially relevant links from topically related sites, which naturally improves DA as a byproduct. We've seen domains jump from DA 15 to DA 35 within 12–18 months through consistent content partnerships and digital PR, but we measure success by organic traffic and rankings, not the score itself. Competing metrics exist, including Ahrefs' Domain Rating (DR) and Semrush's Authority Score, each using different methodologies. None are perfect predictors. Use DA as a rough comparative benchmark when analyzing competitors or vetting link prospects, not as a target KPI. A DA 40 local service site can easily outrank a DA 60 national competitor for geo-specific queries if the local site has better topical relevance and localized backlinks.