Short answer
Core Web Vitals are three metrics Google publishes to measure page experience: Largest Contentful Paint (loading, good at 2.5 seconds or under), Interaction to Next Paint (responsiveness, 200 milliseconds or under) and Cumulative Layout Shift (visual stability, 0.1 or under). The scores that count come from real Chrome visits, not from a laboratory test.
Also called: CWV, LCP, INP, CLS, Page experience metrics
That last distinction is where most reporting goes wrong. A tool like Lighthouse runs one simulated load on a machine you chose and produces a lab score; the field data in Search Console comes from actual visitors on actual devices and connections. A site can score well in the lab and fail in the field because the real audience is on a mid-range Android phone on mobile data rather than on a laptop over fibre.
The usual culprits are unglamorous and fixable: uncompressed hero images, web fonts that block text from painting, third-party tags for chat and analytics, and ads or banners injected after the layout has settled. Google describes page experience as one signal among many rather than an override, so the honest reason to fix these is that slow pages lose visitors before ranking enters the argument.
Common questions
Do Core Web Vitals affect rankings?
They are part of Google’s page experience signals, which are one input among many rather than a decisive one. Relevance and content quality still dominate. Where the metrics matter most is between pages that are otherwise comparable, and in the plainer commercial effect of visitors abandoning a page that takes too long.
Where do we check our own scores?
Google Search Console reports field data from real Chrome visitors, grouped by URL pattern, and PageSpeed Insights shows both field and lab results for a single page. Field data needs enough traffic to report, so a new or low-traffic site may show lab results only.
Where this comes up in our work
Related terms
Server-Side Rendering (SSR) vs Static Site Generation (SSG)
Server-side rendering builds each page when a visitor requests it, so the content reflects the database at that moment.
Responsive Design
Responsive design is a single website built to reshape itself for whatever screen requests it, rather than maintaining a separate mobile site.
Web Hosting
Web hosting is the paid service that keeps a website’s files on a server connected to the internet so visitors can load them.
Structured Data (Schema Markup)
Structured data is machine-readable markup, usually JSON-LD following the schema.org vocabulary, that states explicitly what a page is about: that this string is a price, that one an opening time, this entity the organisation publishing the page.
Reading definitions because you are scoping a project? Skip ahead and just ask.