In order to make performance evaluation easier, on May 28, 2020, Google launched Core Web Vitals, a set of three user-centric metrics called LCP (or Largest Contentful Paint), FID(or First Input Delay), and CLS (or Cumulative Layout Shift).
They were designed to help focus on the improvements that are most important when it comes to a seamless and enjoyable user experience.
Google began rolling out the Page Experience update on mobile devices between June and August 2021.
