Lesson 14 / 32

Core Web Vitals

Master LCP, FID, and CLS — Google's key metrics for user experience and ranking.

The three Core Web Vitals

LCP (Largest Contentful Paint) — how fast your page renders (target: <2.5s). FID (First Input Delay) — how responsive the page is to user input (target: <100ms). CLS (Cumulative Layout Shift) — visual stability, e.g., no jank or jumping buttons (target: <0.1).

Why these metrics matter

Google uses Core Web Vitals as ranking signals. Sites with poor vitals rank lower. A slow page doesn't just frustrate users; it hurts SEO. Developers must monitor and optimize these metrics constantly.

Monitor with PageSpeed Insights

Use Google's PageSpeed Insights tool to measure your Core Web Vitals. Test real user data (CrUX) and get actionable optimization recommendations.