To start off, what is Cumulative Layout Shift, or CLS for short? Basically, it’s the unexpected shifting of webpage elements while the page is still downloading. The sort of elements that cause shift is typically fonts, images, videos, contact forms, buttons and other sorts of content.
In the following Google Search Central video, you will be shown how to reduce your website’s CLS. Not only does it cover what it is, but it talks about its common issues and solutions, how you can measure it, and what a good score is.