Core Web Vitals are a set of specific factors that Google considers important in a webpage’s overall user experience. Core Web Vitals are made up of three specific page speed and user interaction measurements: largest contentful paint, first input delay, and cumulative layout shift.
In short, Core Web Vitals are a subset of factors that will be part of Google’s “page experience” score.
Page experience will be a mishmash of factors that Google considers important for user experience, including:
HTTPS: If a page is served over a secure HTTPS connection then it will display a lock icon in the browser address bar.
Mobile-friendliness: Use Google’s mobile-friendly test.
Lack of interstitial pop ups
Safe-browsing: Check the Security Issues report in Search Console for any issues with safe browsing.
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Largest Contentful Paint (LCP):
The amount of time to render the largest content element visible in the viewport, from when the user requests the URL. The largest element is typically an image or video, or perhaps a large block-level text element. This is important because it tells the reader that the URL is actually loading.
First input delay (FID):
The time from when a user first interacts with your page (when they clicked a link, tapped on a button, and so on) to the time when the browser responds to that interaction. This measurement is taken from whatever interactive element that the user first clicks. This is important on pages where the user needs to do something, because this is when the page has become interactive.
Cumulative Layout Shift (CLS):
CLS measures the sum total of all individual layout shift scores for every unexpected layout shift that occurs during the entire lifespan of the page. The score is zero to any positive number, where zero means no shifting and the larger the number, the more layout shift on the page.