They are metrics that CORRELATE somewhat weakly to rankings. They are NOT important as NO search engine uses them as a metric in their ranking algorithms. ...gets the popcorn and wait for the clueless morons to start posting.
PA (Page Authority) and DA (Domain Authority), those two metrics are provided by MOZ. Those metrics are valuable to understand the site authority level. Both are measure on a 100 point scale. More high, more better. For details, visit : https://moz.com/learn/seo/domain-authority https://moz.com/learn/seo/page-authority
Domain Authority is a score (on a 100-point scale) developed by Moz that predicts how well a website will rank on search engines. Use Domain Authority when comparing one site to another or tracking the “strength” of your website over time. We calculate this metric by combining all of our other link metrics—linking root domains, number of total links, MozRank, MozTrust, etc.—into a single score. To determine Domain Authority, we employ machine learning against Google's algorithm to best model how search engine results are generated. Over 40 signals are included in this calculation. This means your website's Domain Authority score will often fluctuate. For this reason, it's best to use Domain Authority as a competitive metric against other sites as opposed to a historic measure of your internal SEO efforts. You can learn more form Moz here: https://moz.com/learn/seo/domain-authority
Hi, DA and PA is calculated mainly based on online-popularity. If you're generating more backlinks on various best relevant and high authority websites then that will help you to increase your DA and PA score of your website.