Core Web Vitals are a set of metrics Google uses to measure real-world user experience, and by now they are also a ranking signal. But treating them purely as an SEO checkbox misses the point — they measure things visitors genuinely feel.
The three metrics, in plain terms
- Largest Contentful Paint (LCP) — how long until the main content is visible. Slow LCP feels like “is this page even loading?”
- Interaction to Next Paint (INP) — how responsive the page feels when clicked or tapped. Poor INP feels like a laggy, unresponsive app.
- Cumulative Layout Shift (CLS) — how much content jumps around while loading. High CLS is the frustrating experience of clicking a button just as an ad loads and shifts it away.
Common causes worth checking first
Oversized hero images and web fonts loading late are the usual LCP culprits. Heavy third-party scripts (chat widgets, ad networks, tracking pixels) are the most common cause of poor INP. Images and ads without reserved dimensions are almost always behind CLS problems.
Measure before you optimize
It is tempting to guess at fixes, but Google’s free PageSpeed Insights and Search Console both report real Core Web Vitals data from actual visitors. Start there, fix the specific metric that is failing, and re-measure — rather than optimizing blindly.