Domain Authority is a proprietary metric created by Moz that predicts how well a site will rank in search results on a 1–100 scale. To find it, install the free MozBar browser extension and navigate to any website—DA appears in the toolbar. For bulk checks or deeper analysis, use Moz's Link Explorer (10 free queries per month) or subscribe to their paid plans starting around $99 USD monthly. If you use other SEO tools, Ahrefs offers Domain Rating (DR) and Semrush has Authority Score, both using similar 0–100 scales but different algorithms. Ahrefs weighs the quality and quantity of referring domains heavily, while Semrush factors in organic search traffic and backlink quality. These numbers rarely match exactly—a site might score DA 45, DR 52, and Authority Score 38—because each tool crawls the web differently and applies its own weighting. At Ottawa SEO, we track DR primarily since we use Ahrefs for link prospecting across our 500+ domain portfolio, but we cross-reference DA when evaluating link-building targets for clients. A DA jump from 25 to 35 typically requires dozens of quality backlinks from domains scoring 40+, and movement slows dramatically above DA 50. Important caveats: DA is not a Google ranking factor. Google uses its own internal authority signals that no third party can see. DA correlates with rankings but doesn't cause them. Also, brand-new domains start at DA 1 and take months to move even with good links, while aged domains may retain inflated DA despite losing relevance. When prospecting for backlinks, don't chase DA alone—check organic traffic (via Semrush or Ahrefs), topical relevance, and whether the site still publishes fresh content. A DA 60 news site that hasn't updated since 2019 is worth less than a DA 35 industry blog posting weekly. For Canadian businesses, DA matters more for competitive niches like legal, real estate, or finance in Toronto or Vancouver. Local service businesses in smaller markets can rank well with DA 20–30 if they nail on-page SEO and earn locally relevant links.