CLS (Cumulative Layout Shift)
Definition
Cumulative Layout Shift measures how much visible content unexpectedly moves during the page’s life as elements load or change size.
By Vinespire Editorial Team, Editorial ·
This term is part of the full AI search glossary.
Full definition
Layout shifts happen when images lack dimensions, ads inject without reserved space, web fonts swap late, or dynamic banners push content down. CLS aggregates those shifts into a score; lower is better.
Fixing CLS usually means size attributes or aspect-ratio boxes for media, stable ad slots, font strategies that avoid late reflow, and avoiding inserting content above existing content without user action.
Stable pages improve trust and readability when users land from search or AI citations. See Core Web Vitals and LCP.
Example
Reserving a fixed-height container for a late-loading cookie banner prevents the article headline from jumping after first paint.