What are the key takeaways from this guide?

Google Images drives approximately 22% of all web searches.. Alt text serves two purposes: it describes the image for visually impaired users (accessibility) and provides context for search engines.. Search engines use filenames as a relevance signal.. Use `srcset` and `sizes` attributes to serve appropriately sized images for each device:. Add `loading="lazy"` to below-the-fold images..

Who is this guide for?

This guide is designed for beginner-level users and takes about 1 minutes to read.

How-To Beginner 1 min read 283 words

Image SEO: Alt Text, Filenames, and Compression

Images generate significant search traffic through Google Images and enhance page relevance signals. Optimizing alt text, filenames, and compression improves both accessibility and rankings.

Key Takeaways

Google Images drives approximately 22% of all web searches.
Alt text serves two purposes: it describes the image for visually impaired users (accessibility) and provides context for search engines.
Search engines use filenames as a relevance signal.
Use `srcset` and `sizes` attributes to serve appropriately sized images for each device:
Add `loading="lazy"` to below-the-fold images.

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Why Image SEO Matters

Google Images drives approximately 22% of all web searches. Properly optimized images also enhance the page's topical relevance, improving organic rankings for the page itself.

Alt Text Best Practices

Alt text serves two purposes: it describes the image for visually impaired users (accessibility) and provides context for search engines.

Do	Don't
Describe the image accurately	Start with 'image of' or 'photo of'
Include relevant keywords naturally	Stuff keywords unnaturally
Keep under 125 characters	Leave alt text empty on informative images
Leave decorative images alt=""	Add alt text to purely decorative images

Good example: alt="Golden retriever puppy playing fetch in a park" Bad example: alt="dog puppy pet animal cute buy dog food cheap"

Filename Optimization

Search engines use filenames as a relevance signal. Before uploading:

Use descriptive names: golden-retriever-puppy.webp not IMG_4523.jpg
Separate words with hyphens
Use lowercase letters only
Include the primary keyword

Compression and Format

Format	Best For	Compression
WebP	Photos and illustrations	25-34% smaller than JPEG
AVIF	High-quality photos	30-50% smaller than JPEG
SVG	Icons and logos	Infinitely scalable
PNG	Screenshots with text	Lossless, larger files

Responsive Images

Use srcset and sizes attributes to serve appropriately sized images for each device:

Lazy Loading

Add loading="lazy" to below-the-fold images. Never lazy-load the LCP image (usually the hero image) as it delays the largest contentful paint.