What are Core Web Vitals?

Core Web Vitals are a set of metrics from Google that assess how comfortable it is for a user to interact with a site. These metrics directly affect SEO.

Here are the three main ones:

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#1. LCP (Largest Contentful Paint)

What it measures: how many seconds it takes for the page's main content to load. Good: up to 2.5 seconds. Why: if the heading or image appears with a delay, the user leaves.

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#2. FID (First Input Delay)

What it measures: the delay between the user's first action (click, tap) and the page's response. Good: up to 100 ms. Why: if a button responds with lag, the site feels "sluggish."

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#3. CLS (Cumulative Layout Shift)

What it measures: how much the layout "jumps" during loading. Good: up to 0.1. Why: if text or buttons shift, a person may click the wrong thing - it's annoying.

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All of these metrics are checked by Google and can be decisive in ranking. Especially on mobile.