The software company Moz developed a score called Page Authority (PA) to determine and predict the way in which certain website pages will perform on search engine result pages. Machine learning is used to rank each page of your website somewhere between 1 and 100, with the highest score indicating that website pages ability to rank (the highest page authority score is 100 and the lowest is 0).
Your page authority score will change over time depending on your content, links to your website and website pages as well as your competitors scores. Page Authority is distinct from Domain Authority because it “measures the predictive ranking strength of a single page” while “Domain Authority measures the strength of entire domains or subdomains”( https://moz.com/learn/seo/page-authority).
Similar to Domain Authority, Page Authority score should be used as a comparative measure against your competitors, as it is very difficult for small to medium sized businesses to reach a high score close to 100.
While it is challenging to actively change your Page Authority, the best way to do so is to increase the number of external links from other high quality pages that are directing people back to your website and website pages. This validates and legitimizes the content on your site both for the machine learning that determines you Page Authority but also for the people who are visiting your website and your competitors.
You can check your page authority ranking on a website created by Moz at: https://moz.com/link-explorer#index. This site also shows your domain authority, backlinks to your website, keyword suggestions to increase your page authority and domain authority and other useful search engine optimization information for your website and each of its corresponding webpages.