Cumulative Layout Shift (CLS)
Cumulative Layout Shift (CLS) measures visual stability and layout shifts on a webpage.
Definition
Cumulative Layout Shift (CLS) is a metric that quantifies the visual stability of a webpage. It measures the sum of all individual layout shifts that occur 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. A good CLS score is below 0.1, indicating a stable layout. High CLS can frustrate users, especially if they are trying to click on links or buttons that unexpectedly move.
Why It Matters
CLS is an essential metric for SEO as it directly affects user experience. A low CLS score means fewer unexpected shifts, leading to a smoother and more enjoyable browsing experience. Search engines like Google consider CLS as part of their Core Web Vitals, influencing rankings and site visibility.
Example
For example, if an image loads after text and causes the text to move down, that counts towards your CLS score. Tools such as Web.dev can assist in analyzing your CLS and suggest fixes.
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