Largest Contentful Paint
A Core Web Vital measuring the render time of the largest image, video poster or text block visible in the viewport; good is 2.5 s or less…
TechnicalDeferred loading
Lazy loading
Deferring the download of offscreen images and iframes until they are near the viewport, using the native `loading="lazy"` attribute or IntersectionObserver.
In full
Native lazy loading is supported across current browsers and requires no JavaScript. The critical rule is never to lazy-load the LCP element or anything above the fold, because doing so delays the very resource the metric measures — use `loading="eager"` and `fetchpriority="high"` there instead. JavaScript-based lazy loading that never fires for crawlers can also hide images from Google Images entirely.
Example
A gallery marks the first three images eager and the remaining forty `loading="lazy"`, cutting initial payload by 4 MB.
Related terms
srcset and sizes
HTML attributes that offer the browser multiple image candidates at different widths so it can pick the smallest file that fits the layout…
Image and video sitemap extensions
Namespace extensions to XML sitemaps that declare images and videos associated with a page so they can be discovered for Images and Video…
Core Web Vitals
Google's set of three field-measured user experience metrics — LCP, INP and CLS — used as part of the page experience signals in ranking.
JavaScript rendering
The execution of a page's client-side JavaScript by a search engine so that content and links generated at runtime become indexable.