Domain authority matters because it's the best publicly available proxy for a site's ranking power. Created by Moz, DA scores sites 1–100 based on backlink quality, quantity, and diversity. A site with DA 60 will almost always outrank a DA 25 competitor for the same keyword, all else equal. That's why SEO agencies track it obsessively and why link building focuses on moving the needle from, say, DA 18 to DA 35 over 12–18 months. The practical value shows up in three areas. First, higher DA sites rank faster for new content because Google already trusts the domain. Second, they pass more equity through outbound links, so a backlink from a DA 70 news site moves rankings more than ten links from DA 15 blogs. Third, DA correlates strongly with organic traffic potential. A local Ottawa contractor jumping from DA 12 to DA 28 might see traffic double because they suddenly compete for commercial terms they couldn't touch before. But DA has limits. Google doesn't use Moz's score in its algorithm; it calculates its own version of domain trust using hundreds of signals. You can game DA somewhat by acquiring spammy links from high-DA sites, but Google sees through that and those links won't help rankings. Also, DA is relative and recalculated constantly. If your DA drops from 32 to 30, it might just mean competitors built better links, not that you lost authority. At Ottawa SEO, we track DA monthly but never optimize for DA alone. We build links that improve both DA and actual rankings: guest posts on relevant DA 40–60 sites, digital PR placements, and niche edits in established content. The goal is DA 30+ for local businesses and DA 45+ for national brands, but the real test is whether page-one rankings and traffic follow. DA is the scoreboard, not the game.