Alt text (alternative text) is a written description added to an image’s HTML code that tells search engines and screen readers what the image shows. It improves both image SEO and website accessibility.
What Is Alt Text?
Alt text is the text that appears in place of an image when it cannot load and is read aloud by screen reader software for visually impaired users. From an SEO perspective, since Google cannot literally see images the way humans do, alt text is the primary signal Google uses to understand what an image contains and whether it is relevant to the surrounding content.
Why It Matters for SEO
- Google uses alt text to understand image content well-written alt text can rank your images in Google Image Search, driving additional organic traffic
- Alt text contributes to overall page relevance. Images with descriptive alt text reinforce the topic of your content
- Accessibility compliance: Many regions legally require accessible alt text for public-facing websites
- Improves Core Web Vitals indirectly: browsers reserve correct space for images with dimensions set alongside alt text
| Example: Wrong: alt=’image1.jpg’ | Correct: alt=’Google Search Console page indexing report showing crawled not indexed status’ |
How to Write Good Alt Text
- Describe what is actually in the image; be specific and accurate
- Include your target keyword naturally if it genuinely describes the image; never force it
- Keep it under 125 characters; screen readers typically cut off longer descriptions
- Do not start with ‘image of’ or ‘picture of.’ Google and screen readers already know it is an image
- Leave alt text empty (alt=”) for purely decorative images that add no content value
FAQs
Is alt text a ranking factor?
Alt text is not a direct ranking factor for main search results, but it is the primary ranking signal for Google Image Search. It also contributes to overall page relevance signals.
Should every image have alt text?
Every content image should have descriptive alt text. Purely decorative images (like dividers or background patterns) should use empty alt text: alt=” so screen readers skip them.
Related Terms: Image SEO · Accessibility · On-Page SEO · Core Web Vitals
