Alt Text
Alt text is the HTML text description of an image that helps screen readers, appears when an image fails to load, and gives search engines more context about the image.
Key takeaways
- Alt text improves accessibility for screen reader users and helps search engines index images.
- Write natural, descriptive alt text—never keyword stuff.
- Use empty alt for decorative images only.
- Keep it concise: under 125 characters is a good rule.
- Avoid 'image of' or 'picture of'—screen readers already announce images.
Alt text is a small HTML attribute with a big impact on both user experience and search visibility.
Example of Good Alt Text
- Image: A golden retriever puppy sitting on a green lawn holding a red ball in its mouth.
- Good alt text: "Golden retriever puppy holding a red ball on grass."
- Bad alt text: "Dog" (too vague) or "puppy dog pet animal cute" (keyword stuffing).
When Should I Use Alt Text?
- Always for informative images (charts, product photos, infographics).
- Always for images that contain text (e.g., a screenshot of a quote).
- Always for images that are links (describe the link destination).
- Use empty alt (
alt="") for purely decorative images (background patterns, spacers).
What Alt Text Is Not
- Not a place to stuff keywords.
- Not the same as the image file name or caption.
- Not a tooltip (that's the title attribute).
- Not optional for accessibility—it's required for screen reader users.
Quick Start: How to Write Alt Text
- Look at the image and describe what you see.
- Be specific—include relevant details (color, action, context).
- Keep it short—aim for under 125 characters.
- Include keywords naturally if they fit the description.
- Skip filler phrases like "image of" or "picture of."
- Test with a screen reader or ask someone to describe the image from your alt text.
Common Alt Text Mistakes to Avoid
- Keyword stuffing: "Buy cheap red sneakers online" instead of "Red running shoes on a track."
- Vague descriptions: "Photo" or "Image" instead of "Sunset over the Grand Canyon."
- Empty alt for important images: Leaving alt blank on a chart or product photo.
- Repeating captions: Alt text should add value, not duplicate nearby text.
Next step
FAQ
What is alt text for images?
Alt text (alternative text) is an HTML attribute added to an image tag that provides a text description of the image. It is used by screen readers for accessibility and by search engines for indexing.
How do I write alt text for SEO?
Write alt text that accurately describes the image while naturally including relevant keywords. Avoid keyword stuffing. Keep it concise and descriptive.
What is the difference between alt text and title text?
Alt text describes the image for accessibility and SEO. Title text provides additional information as a tooltip when hovering over the image. They serve different purposes.
Related topics
Sources
- Google Search Central — Most authoritative source for how Google handles image and on-page SEO signals.
- WebAIM — Widely cited accessibility authority for writing effective alt text.
- W3C WAI — Standards-based guidance on accessible images and alternative text.
- Yoast — Well-known SEO reference that explains image optimization and practical CMS usage.
- Ahrefs — Clear SEO-focused guidance on best practices and common alt text mistakes.
Reviewed by Lucía Marín, Founding editor.