Domain Authority (DA) is a search engine ranking score developed by Moz that predicts how well awebsite will rank on search engine result pages (SERPs). A Domain Authority score ranges from one to 100, with higher scores corresponding to a greater ability to rank.
Domain Authority is calculated by evaluating multiple factors, including linking root domains and number of total links, into a single DA score. This score can then be used when comparing websites or tracking the “ranking strength” of a website over time. Domain Authority is not a metric used by Google in determining search rankings and has no effect on the SERPs.
You can view a website’s DA by using MozBar (a free Chrome-extension), Link Explorer (a backlink analysis tool), the SERP Analysis section of Keyword Explorer, and dozens of other SEO tools across the web.
Domain Authority is based on data from our Link Explorer web index and uses dozens of factors in its calculations. The actual Domain Authority calculation itself uses a machine learning model to predictively find a “best fit” algorithm that most closely correlates our link data with rankings across thousands of actual search results that we use as standards to scale against.
Since Authority is based on machine learning calculations, your site’s score will often fluctuate as more, less, or different data points are used in the calculation — for instance, if Facebook were to acquire a billion new links, everyone’s PA and DA would drop relative to Facebook. For this reason, keep in mind that you should always use Domain Authority as a relative metric to compare against the link profiles of other sites, as opposed to an absolute value scoring the efficacy of your internal SEO efforts.