Cumulative Layout Shift (CLS)
A Core Web Vital that measures visual stability by quantifying unexpected layout shifts.
Quick Definition
A Core Web Vital that measures visual stability by quantifying unexpected layout shifts.
Full Explanation
Cumulative Layout Shift (CLS) is one of Google's three Core Web Vitals metrics that measures visual stability. CLS quantifies how much unexpected layout shift occurs during the entire lifespan of a page. A layout shift happens when a visible element changes its position from one rendered frame to the next. CLS is calculated by multiplying the impact fraction by the distance fraction. A good CLS score is under 0.1. Common causes include images without dimensions, ads or embeds without reserved space, dynamically injected content, and web fonts causing FOIT/FOUT. To fix CLS, always include width and height on images, reserve space for dynamic content, and use font-display strategies.
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Largest Contentful Paint
A Core Web Vital that measures how long it takes for the largest content element to become visible.
Interaction to Next Paint
A Core Web Vital that measures page responsiveness by tracking the latency of user interactions.
Core Web Vitals
A set of three metrics (LCP, INP, CLS) that Google uses to measure user experience and as ranking factors.