Core Web Vitals
Core Web Vitals are Google's three metrics for real-world page experience: loading, responsiveness, and visual stability.
In full
Core Web Vitals are three metrics Google uses to quantify page experience using data from real visitors. Largest Contentful Paint measures how long until the main content appears, with under 2.5 seconds considered good. Interaction to Next Paint measures how quickly the page responds when someone taps or clicks, with under 200 milliseconds considered good. Cumulative Layout Shift measures how much the layout moves while loading, with under 0.1 considered good. A page passes when the 75th percentile of real visits meets all three thresholds, which means the metrics must hold up on slower devices and connections rather than only on fast ones.
Why it matters
They are a ranking input, though a modest one relative to relevance. The stronger argument is commercial: slow, unstable pages lose visitors and conversions regardless of where they rank.
A common misconception
That First Input Delay is still one of them. Interaction to Next Paint replaced FID in March 2024 and is a considerably harder metric, because it measures responsiveness across the whole visit rather than only the first interaction.