Domain Authority
Domain authority is a score, computed by third-party SEO tools, that estimates how likely a whole website is to rank in search results, mainly from the number and strength of the links pointing at it. It is a vendor’s estimate, not a figure any search engine or AI assistant publishes or confirms.
Where the number comes from
Each tool that sells one builds it from its own crawl of the web: how many distinct sites link to the domain, how strong those linking sites are by the same measure, and a scaling so the result fits a 0 to 100 range. Two tools give two different numbers for the same site, because they have crawled different parts of the web and weighted them differently. The score is useful for comparing two sites inside one tool, and for watching one site over time in that tool. It is not a measurement of anything a search engine does.
What Google says it uses
Google’s guide to its ranking systems lists PageRank among the link-analysis systems it has used since launch, and says its ranking systems work at the page level, with site-wide signals and classifiers contributing to how pages are understood. It adds that good site-wide signals do not guarantee a high ranking for every page on the site, nor poor ones a low ranking. There is no site-wide authority score in the list. The idea behind domain authority, that a strong site lifts its pages, is a rough model of the site-wide signals Google describes; the number itself is the vendor’s.
A common question
Does domain authority decide whether an AI assistant cites a site?
No assistant documents using a vendor’s score, and none publishes one of its own. What is documented is the sequence: the assistant searches, fetches a handful of pages, and chooses passages from them. Links help a page get found and ranked in the first step, so a well-linked site is more likely to be fetched. Whether it is then quoted depends on whether a passage on the page answers the question, and no domain-wide number describes that.
Related terms
Sources
Page-level ranking and site-wide signals: Google Search Central, ranking systems guide. No figures on this page are this site’s own.