What you need to know
Layout shifts make people lose their place or click the wrong control. They often come from media with unknown dimensions, injected banners, or fonts that change text wrapping.
How to apply it
Set image aspect ratios and dimensions, reserve space for ads or widgets, and avoid inserting content above what a user is reading. Check the page while it loads, not only after everything settles.
Common mistake to avoid
Do not fix shifts by hiding content until load. That can make the page appear slower and can cause accessibility problems.