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Image SEO is a consistently overlooked traffic channel. Google Images drives billions of searches monthly, and well-optimized images also boost the ranking of the pages they appear on. Every image on your site is an opportunity — for image search traffic, improved page relevance, and enhanced user experience.
Image SEO Fundamentals
File Names
Name image files descriptively before uploading. Use hyphens to separate words. “keyword-research-process-diagram.webp” is far more informative to search engines than “IMG_4521.jpg.”
For more on this topic, see our guide on progressive web app seo.
For more on this topic, see our guide on technical seo audit.
For more on this topic, see our guide on mobile first indexing seo.
For more on this topic, see our guide on enterprise seo strategy.
Alt Text
Alt text serves two purposes: accessibility (screen readers) and SEO (image context for search engines). Write alt text that accurately describes the image while naturally including relevant keywords.
- Good: “Flowchart showing the six phases of keyword research from seed discovery to content mapping”
- Bad: “keyword research keyword strategy SEO keywords”
- Also bad: “image” or leaving alt text empty
Image Format and Compression
- WebP: Best balance of quality and file size for most use cases
- AVIF: Even better compression, growing browser support
- SVG: Ideal for logos, icons, and illustrations (vector, infinitely scalable)
- PNG: When transparency is needed and WebP isn’t supported
Compress all images to the smallest file size that maintains acceptable quality. Use responsive images (srcset) to serve appropriate sizes per viewport.
Lazy Loading
Add loading="lazy" to images below the fold. This improves initial page load speed (LCP) without sacrificing content. Never lazy-load above-the-fold hero images.
Dimensions
Always specify width and height attributes to prevent Cumulative Layout Shift (CLS). The browser reserves space for the image before it loads, preventing layout jumps.
Advanced Image SEO
- Structured data: Use ImageObject schema to provide additional context
- Image sitemaps: Help search engines discover images, especially for dynamic or JavaScript-rendered content
- Captions: Text near images provides contextual signals — use descriptive captions
- Original images: Unique images perform better in image search than stock photos used across thousands of sites
Image SEO is low effort, high impact. A few minutes spent on file naming, alt text, and compression per image compounds into significant traffic over time, especially for content-heavy sites with hundreds of images.
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