Domain Authority is a 1–100 score created by Moz that predicts how likely a website is to rank, based mainly on its links.
DA is a third-party metric, not something Google uses. Ahrefs (Domain Rating) and Semrush (Authority Score) have similar metrics calculated from their own link indexes, so the numbers differ between tools.
DA rises when a site earns links from many different reputable websites. It is useful for comparing sites, but rankings depend on many other factors such as relevance and content quality.
SEO is the work of improving a website so it appears higher in unpaid search results for the searches its customers make.
SEOTechnical SEO makes sure search engines can find, crawl, render and index a website’s pages without problems.
SEOOn-page SEO is optimising the content and HTML of individual pages so they match what searchers are looking for.
SEOOff-page SEO is everything done outside your own website to build its authority, mainly earning links and brand mentions.
