Cyrus-Shepard wrote:

What are Core Web Vitals?

So these are real-world experience metrics that Google is looking at, that answer things like: How fast does the page load? How fast is it interactive? How fast is it stable? So basically, when visitors are using your web page on a mobile or a desktop device, what's that experience like in terms of speed, how fast can they interact with it, things like that.

Now it's joining a group of metrics that Google calls Page Experience signals. It's not really a standalone. It's grouped in with these Page Experience metrics that are separate from the text on the page. So these are signals like mobile friendliness, HTTPS, intrusive interstitials, which are those pop-ups that come on and appear.

It's not so much about the text of the page, which are traditional ranking signals, but more about the user experience and what it's like, how pleasant it is to use the page, how useful it is. These are especially important on mobile when sometimes the speed isn't as high. So that's what Google is measuring here. So that's what it is.