Core Web Vitals. LCP, INP, CLS. It sounds like a diagnostic code and that is a shame, because all three describe things you have personally been annoyed by this week.
LCP. How long until I see the thing
Largest Contentful Paint. In English: how long before the main thing on the page shows up. Usually your hero image or your headline.
You want under two and a half seconds. Over four and people are leaving.
The cause is almost always a giant hero image or a slow server. Fix the image, then look at hosting. Not the other way around.
INP. How long until my tap does something
Interaction to Next Paint. You tap a menu and nothing happens for a beat, so you tap again, and now the menu opens and closes.
That is the browser being too busy running JavaScript to respond to you. Which means the cause is usually too many scripts, and the fix is usually deleting some.
Tracking pixels, chat widgets, four analytics tools, a review widget, a popup manager. Each one is fighting for the same thread that your tap needs.
CLS. The page jumping around
Cumulative Layout Shift. You go to tap a link, an ad or an image finishes loading above it, everything slides down, and you tap the wrong thing.
Infuriating, and almost entirely caused by images without declared dimensions. The browser did not know how much room to reserve, so it reflowed everything once it found out.
Put width and height on your images. That is most of the fix. Late loading web fonts and injected banners are the rest.
Does it actually affect rankings
Yes, and less than people say. It is a tiebreaker, not a main ingredient. Relevance and links matter more.
But it absolutely affects whether somebody stays, and that shows up in your business whether or not it shows up in your rankings.
The ten second version
Pull your site up on your own phone, off wifi. Does the main thing appear fast. Does a tap respond right away. Does anything jump while it loads.
You just measured all three. No dashboard required.