What is domain authority?
A third-party estimate of how strong a site's link profile is, on a scale of one to a hundred. Useful for comparing sites; not a Google metric and not something Google reads.
Domain authority is a score created by an SEO software company, not by Google. Other tools have their own versions under different names. Each one is that company’s attempt to estimate how strong a site’s link profile is, based on the links their own crawler has found.
It is useful as a rough comparison. If you are looking at two sites in the same market, the one with a much higher score usually has a stronger set of links behind it.
The mistake is treating it as a ranking factor. Google does not read it and has said as much. A site can have a modest score and rank very well for exactly the searches that matter to it, and a site with a high score can rank for nothing useful. Buying links to push the number up is chasing a third party’s estimate of the thing rather than the thing itself. What Google actually works from is its own version of PageRank.
Search that compounds, run by people who show their work.
Strategy, technical, content, links and local, planned together and reported against the numbers your business cares about.