What are Core Web Vitals?
Core Web Vitals are Google's three metrics for real-world page experience: how fast content loads, how quickly the page responds to input, and how much the layout shifts while loading.
The three are Largest Contentful Paint, measuring load speed; Interaction to Next Paint, measuring responsiveness; and Cumulative Layout Shift, measuring visual stability. Google has confirmed they are a ranking factor, which is why they get treated as urgent, but the company has also said they are a small factor among many and mainly act as a tiebreaker between pages that are already relevant.
They are measured by loading and rendering a page, which means they say nothing about whether an AI crawler can read it. Most AI crawlers fetch raw HTML and do not render or time a page the way Core Web Vitals require, so a page can pass every threshold and still be unreadable to those crawlers if its content depends on client-side rendering, and the reverse holds too: a slow page can be perfectly citable if its content is already in the initial HTML.
Related
- Server-side renderingServer-side rendering means the HTML arrives complete from the server. It matters because most AI crawlers do not execute JavaScript, so content injected in the browser is invisible to them.
- Mobile-first indexingMobile-first indexing means Google indexes a page using the mobile version of its content, not the desktop one, even for a search happening on a desktop.
- AI crawlerAn AI crawler is a bot operated by an AI company to fetch web pages for training, indexing, or answering a live question.
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