Page Speed & Core Web Vitals tools

What Core Web Vitals tools do

Everything in this category splits on one distinction, and most confusion about it comes from missing that split. Lab data is a single simulated visit on known hardware: repeatable, diagnostic, and available before a page is public. Field data is what real users experienced, aggregated over weeks: noisy, undiagnostic, and the thing Google actually uses. A lab score of 100 alongside failing field metrics is not a contradiction. It means your users are slower than your test machine, which is normal. So the tools divide by which they give you, and a serious workflow uses both: field data to decide whether there is a problem, lab data to find out what it is. Two further points get missed. Vitals are assessed per URL group rather than per site, so a bad template matters more than a bad average. And these are page-experience signals, not a ranking lever, fixing them rarely moves a page on its own, though failing them badly can hold one back.