 One of the key core of vitals which measures UX performance is CLS or Accumulative Layout Shift. And it measures the instability of a page's content, scoring experiences low if the content is unstable, shifting around, jumping and moving while you're trying to read or interact with it. The worst offender of this being that moment when you were just about to click a button, but then the layout shifts and the button that was under your mouse is no longer under your mouse. It's also a way when you're trying to read something and then it goes away. Totally. You're like reading that headline. You're like, how to do it in the hero image loads and you're just like, where was I in this paragraph? I was somewhere. So here's a high level of those main offenders. There's images, iframes or ads that don't have dimensions. There's ads, embeds and late loaded third party components or content. There's animations and also fonts can be contributing to CLS. Awesome recap.