Image SEO Best Practices: Alt Text, File Names, and Lazy Loading
Optimized images improve search rankings, accessibility, and page speed. Learn how to name, describe, and serve images for maximum SEO benefit.
Key Takeaways
- Search engines use file names as a ranking signal.
- Alt text serves two purposes: accessibility for screen reader users and context for search engines.
- Use the `srcset` attribute to serve different sizes for different devices.
- Add `loading="lazy"` to images below the fold.
- For image-heavy sites, include images in your XML sitemap.
Nén Ảnh
Giảm dung lượng ảnh mà vẫn giữ chất lượng.
File Naming
Search engines use file names as a ranking signal. Name images descriptively: blue-running-shoes-nike-pegasus.webp is far better than IMG_4392.jpg. Use hyphens to separate words and keep names under 50 characters.
Alt Text
Alt text serves two purposes: accessibility for screen reader users and context for search engines. Write alt text that describes what the image shows in 1-2 sentences. Avoid keyword stuffing — describe naturally.
Responsive Images
Use the srcset attribute to serve different sizes for different devices. A phone doesn't need a 4000px image. Providing appropriate sizes reduces bandwidth and improves Core Web Vitals scores.
Lazy Loading
Add loading="lazy" to images below the fold. This defers loading until the image is about to enter the viewport, significantly improving initial page load time. Never lazy-load the LCP (Largest Contentful Paint) image.
Image Sitemaps
For image-heavy sites, include images in your XML sitemap. This helps search engines discover images that might be loaded dynamically or embedded in JavaScript galleries.
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