Core Web Vitals are three measurements Google collects from real visits to a public page. They ask whether the main content showed up promptly, whether the page answered a click or a tap, and whether the layout jumped while it was loading. The names are LCP, INP, and CLS. You do not need the names to feel the failures. A hero image that arrives late, a button that ignores the first tap, a form that leaps down the screen as a banner loads: that is the subject.
Field data, not a demo on a fast laptop
A score run once, on an office connection, from a developer machine, is a lab result. It is useful while you are fixing a page. It is not what Google publishes for the site. The number that matters is the experience of people on the phones and networks you actually have. Search Console's field report is that number. A green badge from a single test is a photograph of a good afternoon.
The longer account of what to change, and what to ignore, is Core Web Vitals explained.
Where they count, and where they do not
They count on pages you want strangers to find: the homepage, a service page, a guide. A slow public page is both a bad visit and a weaker candidate in search. They are a weak way to judge a portal behind a login. Staff will complain if the screen is slow. Google is not ranking that screen. Do not spend the month chasing a perfect score on an internal tool while the public site still shifts under the reader's thumb.
They are also not a design trend. Compressing an image, reserving space so the page does not jump, and not loading a pile of scripts you do not use will do more than a new framework. The framework is sometimes the reason the page is heavy.
When it matters on a project
Treat them as a requirement on a public website from the first layout, not as a report you commission after launch. A layout that loads a banner above the title will jump. Decide the space before the banner exists. On an internal system, measure the task: can someone finish the job without waiting. That is a different test, and it is the one the staff will notice.
If a vendor promises "we will pass Core Web Vitals" without saying which pages and which field report, ask to see the Search Console view, not a screenshot from their laptop.