Domain Authority (DA) is a MOZ developed, 0-100 scale, search engine ranking score, that assigns a score to every website domain as a whole on the Internet, calculated by an algorithm including linking domain metrics, content quality, meta information, NAP listings, citations, and more. The higher the DA, the more credible, authoritative, and reputable the website domain is deemed in the search engine's eyes, while also giving it a higher likelihood of ranking higher on keyword search terms. Long story short, the higher the DA, the better off your website's SEO will be.