CLS is a metric that defines visual stability. Quite literally, this means that content should be stable and readable within a page. If a page’s continual loading causes text and images to jump around or change the dynamics of your page, then users can find themselves losing their place or frustratingly clicking in the wrong places at the last second. CLS measures the largest layout shift that occurs during the lifespan of a page’s activity. Sites with a layout shift score over 0.1 are considered unstable and need improvement.