CLS (Cumulative Layout Shift)
Definition
CLS is a Core Web Vitals metric that measures how much visible page content shifts unexpectedly during loading.
Plain English
It scores how "jumpy" your page feels. Lower is better.
Why it matters
- High CLS frustrates users who click the wrong thing.
- It's one of three Core Web Vitals that affect search quality signals.
- Common causes: images without dimensions, late-loading ads, web fonts.