Images drive 20% of web search traffic and Google Lens searches grew 200% YoY. Yet most WordPress sites still serve uncompressed PNGs. Here is the complete image SEO playbook.
Image search accounts for roughly 20% of all web search queries. Google Lens usage grew 200% year-over-year. Image SEO is no longer about alt tags alone — it involves format selection, delivery optimization, structured data, and visual search readiness. Here is the 2026 playbook.
| Format | Compression | Browser Support (2026) | Best For |
|---|---|---|---|
| AVIF | Best (50% smaller than JPEG) | 92% (all except IE) | Photographic content, hero images |
| WebP | Good (30% smaller than JPEG) | 97% (universal) | General use, safe default |
| JPEG | Baseline | 100% | Fallback for unsupported browsers |
| PNG | Poor (large files) | 100% | Transparency, logos, screenshots |
| SVG | N/A (vector) | 98% | Icons, logos, illustrations |
Recommendation: Serve AVIF with WebP fallback. WordPress 6.5+ supports AVIF natively. Use the <picture> element to provide both formats. If your hosting does not support AVIF encoding, WebP is a safe default that works everywhere.
WordPress 5.5 added native lazy loading via loading="lazy". But Google's 2024 update changed the guidance: do not lazy load the first image above the fold. Lazy loading above-the-fold images delays LCP, which directly affects Core Web Vitals.
| Image Position | Lazy Load? | Priority Hint |
|---|---|---|
| Above the fold (LCP image) | ❌ No | fetchpriority="high" |
| Below the fold | ✅ Yes | loading="lazy" |
| Carousel/slider first slide | ❌ No | fetchpriority="high" |
| Carousel subsequent slides | ✅ Yes | loading="lazy" |
Alt text serves two purposes: accessibility (screen readers) and image search (Google Images, Google Lens). The 2026 best practice is not to stuff keywords into alt text. It is to describe the image accurately and let keywords appear naturally.
| Bad Alt Text | Good Alt Text |
|---|---|
| "red shoes buy online cheap" | "Red canvas sneakers with white sole on wooden floor" |
| "espresso machine" | "Stainless steel semi-automatic espresso machine with portafilter" |
| "logo" | "Shop2LLM logo — blue gradient circle with white text" |
Google's 2025 image search update placed more weight on contextual relevance — the alt text must match the surrounding content. Keyword-stuffed alt text that does not match the page topic is now a negative signal.
For product images, e-commerce sites should use ImageObject schema:
| Schema Field | Required? | Why It Matters |
|---|---|---|
| url | ✅ | Canonical image URL |
| caption | Optional | Appears in image search results |
| representativeOfPage | Optional | Tells Google this is the main product image |
| width / height | ✅ | Prevents CLS (layout shift) |
Google Lens processes over 12 billion visual searches per month. Users point their camera at a product, and Google matches it against product images in its index. To be discoverable via Google Lens:
red-canvas-sneakers-front-view.jpg is better than IMG_3471.jpg.