Why it matters
On the web, speed is trust. CLS sits squarely in how fast and stable a page feels, and that perception decides whether a visitor stays or leaves before the first interaction. Search engines reward the same qualities people do, so getting CLS right tends to lift both experience and rankings at once.
In practice
In practice we treat CLS as a measurable target, not a vibe. We baseline it on real devices and connections, set a budget the whole team agrees to, and check it on every release so a quick win never quietly regresses a few sprints later.