What it is
Domain Authority is a 1-to-100 score that estimates how much ranking strength a website has built up, mostly from the quantity and quality of sites linking to it. Moz created it; Google does not use it. Think of it as a weather forecast for credibility: directional and handy, not a law of physics.
Why it matters
AI systems and search engines both reward sites the web treats as credible. A site with high earned authority gets its pages read, trusted, and cited more readily, which is exactly what you want when an answer engine is choosing one source over another. Chasing the DA number itself is a trap, but the credibility it reflects is real and worth building.
What to do
Stop optimizing for the score and build the thing it measures: earn quality backlinks, publish content worth referencing, and clean up technical issues that hold the whole domain back. Track DA as a trend line over months, not a daily target.