Performance & Core Web Vitals · Glossary term

Image optimization (AVIF / WebP) explained without jargon.

Modern image formats with better compression than JPG. AVIF ~50% smaller than JPG. WebP ~30% smaller, broader browser support.

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Extended definition

Modern image formats with better compression than JPG. AVIF ~50% smaller than JPG. WebP ~30% smaller, broader browser support.

Context and application

WebP has ~98% browser support (all modern browsers since 2020). AVIF has ~93% support (Safari added in 2023). Strategy: serve AVIF primary, fallback to WebP, fallback to JPG with <picture> + <source>. For WordPress, plugins like ShortPixel or Smush convert automatically and serve with picture tag. For custom sites, builds with Astro or Next.js have built-in image optimization (next/image, astro:assets). For decorative images, a reduction from 200KB JPG to 50KB AVIF means 4x faster loading on 4G.

Related terms

LCP, Lazy loading.

Rest of the glossary

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