AVIF
A modern image format based on the AV1 codec that generally compresses better than WebP, with wide but slightly less universal browser…
Technical
WebP
A Google-developed image format supporting lossy and lossless compression plus transparency and animation, typically 25-35% smaller than comparable JPEG or PNG.
In full
WebP has universal support in current browsers and is the safe default modern format. It is delivered either by content negotiation at the CDN using the Accept header, or by a `<picture>` element with a JPEG fallback source. Converting large hero and product images to WebP is one of the highest-leverage LCP fixes on image-heavy sites.
Example
A 1.8 MB PNG product shot re-encoded as WebP at quality 80 drops to 210 KB with no visible difference.
Related terms
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…
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…
Lazy loading
Deferring the download of offscreen images and iframes until they are near the viewport, using the native `loading="lazy"` attribute or…
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…