Core Web Vitals: LCP FID CLS
Understand what Largest Contentful Paint, First Input Delay, and Cumulative Layout Shift measure and why Google uses them as ranking signals.
Why Performance Matters
Slow pages lose users. Google made performance a ranking signal: sites with poor Core Web Vitals scores rank lower in search results. Beyond SEO, every 100ms of delay measurably reduces conversion and engagement.
The Three Core Web Vitals
Google measures three user-experience metrics: LCP (loading speed), FID (interactivity), and CLS (visual stability). Each has 'Good', 'Needs Improvement', and 'Poor' thresholds.
All lessons in this course
- Core Web Vitals: LCP FID CLS
- Lighthouse Audits and Scoring
- Image Optimization: lazy loading formats WebP
- Code Splitting and Lazy Routes