Core Web Vitals are the three metrics Google publishes as ranking signals under the page-experience umbrella. LCP measures load, CLS measures stability, INP measures responsiveness. All three are measured in the *field* — from real Chrome users via the CrUX dataset — for a site to qualify in Search Console's report.
Lab measurements (Lighthouse, ifySEO's own scanner) are useful proxies and are the only signal a low-traffic site has, but they don't always agree with field values because lab tests run on a fixed device profile and don't capture the long tail of real-user conditions.
Targets: LCP ≤ 2.5 s, CLS ≤ 0.1, INP ≤ 200 ms for the 75th percentile of page loads, calculated over a 28-day window.