As a dominant force in the search space, Google has researched in depth what constitutes a superb user experience, arriving at three important factors, which the company calls, collectively, the Core Web Vitals.nnBefore explaining them, I’d like to recommend an informative article, published last May on the Chromium Blog, titled The Science Behind Web Vitals. At the bottom of the piece are links to papers on the research that led to the guidelines for accurately evaluating user experiences.nnNow back to the three Core Web Vitals. The first one affects page-load speed, which Google calls Largest Contentful Paint (LCP) with a recommendation of 2.5 seconds or less for the largest element on a page to load.nnThe second metric is First Input Delay (FID), which is a delta between a user trying to interact with a page, and the browser effectively executing that action. Google recommends 100 milliseconds or less. nnThe third and last metric is Cumulative Layout Shift (CLS), which measures how stable a site is while it’s loading or while you’re interacting with it. In other words it is a measurement of individual layout shifts as well as unexpected layout shifts that happen during the lifespan of a page. The calculation involves impact and distance fractions which are multiplied together to give a final value. Google advocates this value to be 0.1 or less.