Domain Authority (DA) is a score from 0 to 100 that estimates how much trust and authority a domain carries in search engine rankings. Developed by Moz, DA is not an official Google ranking factor, but it is widely referenced in SEO practice.
DA uses a logarithmic scale, so raising a score from 20 to 30 is far easier than going from 70 to 80. Rough benchmarks: new domains score 1-10, small-business sites 20-40, major media outlets 60-80, and sites like Wikipedia or Google exceed 90.
The primary factors behind DA are the quality and quantity of backlinks (links from other sites). Links from high-authority sites boost DA the most. However, buying links or building spammy link networks violates Google's guidelines and can trigger penalties.
The relationship between short URLs and DA is nuanced. Whether a link through a short URL contributes to the destination page's DA depends on the redirect type. A 301 redirect (permanent) passes link juice almost completely, so the impact on DA is minimal. A 302 redirect (temporary) may not transfer link juice fully. When SEO matters, choose a short URL service that uses 301 redirects.
Besides Moz's DA, similar metrics include Ahrefs' Domain Rating (DR) and Majestic's Trust Flow. Each uses its own algorithm, so scores cannot be compared directly across tools. Related books are available on Amazon.