Core Web Vitals are Google's three metrics of perceived page quality: LCP (how fast the main content loads), INP (how fast the page responds to interactions) and CLS (visual layout stability). They influence search rankings.
The "good" thresholds: LCP under 2.5 s, INP under 200 ms, CLS under 0.1. Google measures them on real users (CrUX data), not in a lab – what counts is the actual experience, including on weaker phones and connections.
The usual culprits of poor scores: unoptimised images, JavaScript bloat, render-blocking fonts, ads and banners that shift content (CLS), slow hosting.
Why bother: beyond SEO impact, the same optimisations raise conversion – research consistently shows every second of delay costs sales. We design our sites for a full set of green scores from day one.