What are Core Web Vitals and why do they matter?

Core Web Vitals are three specific metrics Google uses to measure user experience: LCP measures loading performance (should be under 2.5s), FID measures interactivity (should be under 100ms), and CLS measures visual stability (should be under 0.1). They matter because Google uses them as ranking factors—sites with good Core Web Vitals rank higher. They also directly impact user experience—slow, unresponsive sites frustrate users and increase bounce rates. Good Core Web Vitals correlate with better conversions and user satisfaction. Example: A site improving all Core Web Vitals saw 20% lower bounce rate and 15% higher conversion rate, plus improved search rankings.