Performance / CLS
Cumulative Layout Shift
Plain-language definitionA Core Web Vital that measures unexpected movement of visible page content. Reserved media space and stable font loading help reduce it.
Why it matters
Use the term to make a better decision.
In practice, cumulative layout shift matters when a team needs to connect a technical or creative choice to a visible change in clarity, performance, discovery, or conversion. The useful question is not whether the term sounds sophisticated. It is what decision it helps the team make.