Domain Authority (DA) is a score from Moz that estimates how strong a website's backlink profile is, on a scale of 1 to 100. It's a third-party estimate, not a Google metric.
It's similar in spirit to Ahrefs' Domain Rating: both look at how many sites link to a domain and how strong those sites are.
Scores rise slowly as a site earns links from well-linked sites, and the scale gets harder to climb the higher you go.
Why it matters for a launch
It's a quick way to compare sites when deciding where to spend effort on listings and outreach, as long as you remember it's an estimate.
Read more: Free dofollow backlinks for a new site