Core Web Vitals get talked about like a mysterious technical metric, but the underlying idea behind them is actually simple: does your page load quickly, and does it stay visually stable while someone's trying to use it? Here's what the three specific metrics actually measure.
Largest Contentful Paint (LCP): how fast the main content shows up
This measures how long it takes for the biggest visible element on the page — usually a hero image or main heading — to fully load. A slow LCP feels like staring at a half-loaded page, which is exactly the frustration this metric is trying to catch.
Interaction to Next Paint (INP): how responsive the page feels
This measures the delay between someone clicking or tapping something and the page actually responding. A high INP feels like the classic "why isn't this button working" frustration — the click registered, the page just hasn't caught up yet.
Cumulative Layout Shift (CLS): whether things jump around while loading
This measures unexpected layout shifts — the classic experience of trying to tap a button just as an ad or image loads above it and pushes everything down, so you tap the wrong thing entirely. High CLS is one of the more genuinely annoying user experience problems, and it's fully within a developer's control to prevent.
Why these specifically became ranking factors
Google elevated these particular metrics because they map closely to real user frustration, not because they're arbitrary technical trivia. A page that scores well on all three genuinely does feel faster and more stable to use — the ranking benefit is really a byproduct of a better actual experience.
How we approach fixing them
Most Core Web Vitals issues trace back to a small number of causes — unoptimized images, render-blocking scripts, and elements without reserved space before they load. Fixing the underlying cause tends to improve all three metrics together, rather than needing three separate fixes.