What is PageRank (Domain Authority, Domain Rating, Authority Score)?

In a nutshell, PageRank is an algorithm used by Google Search to rank webpages in search engine results. PageRank considers the volume and quality of backlinks and referring domains as endorsements of quality and authority.

It is named after both the term "web page" and co-founder Larry Page. PageRank is a way of measuring the importance of website pages.

According to Google:

“PageRank works by counting the number and quality of links to a page to determine a rough estimate of how important the website is. The underlying assumption is that more important websites are likely to receive more links from other websites.”

Google still uses PageRank internally in their search algorithms, but no longer publicly shares website’s PR. Since PR, and the metrics it uses, are still used by Google internally, other SEO tool vendors have created their own metrics designed to simulate PageRank, including MOZ’s Domain Authority (DA), Ahrefs’ Domain Rating (DR) and Semrush’s Authority Score (AS). These tools are all similar and seek to estimate a website authority based on the volume and quality of backlinks and referring domains.