Alt Attribute SEO
The alt attribute is HTML text added to an image that describes what the image shows or does, so search engines and screen readers can understand it when the image is unavailable.
Key takeaways
- Alt text helps search engines understand images and improves accessibility.
- Write concise, descriptive alt text that naturally includes keywords.
- Use empty alt (
alt="") for decorative images. - Avoid keyword stuffing, vague descriptions, and leaving important images without alt text.
- Alt text is not a ranking guarantee but supports image search and page relevance.
Alt text is a small HTML attribute with a big impact on both SEO and accessibility.
Example
- Image: A photo of a red apple on a wooden table.
- Good alt text:
alt="Red apple on a wooden table" - Bad alt text:
alt="apple"(too vague) oralt="apple fruit healthy food"(keyword stuffed)
When should I use this?
- Every time you add an
<img>tag to a page. - For images that convey information (e.g., product photos, infographics, charts).
- For images that are links (alt text describes the link destination).
- For decorative images, use empty alt (
alt="") to avoid cluttering screen readers.
What it is not
- Not a caption: Captions are visible text near the image; alt text is hidden unless the image fails to load.
- Not a title attribute: The title attribute shows as a tooltip on hover; alt text is for accessibility and SEO.
- Not a keyword-stuffing opportunity: Overloading alt text with keywords harms user experience and can be penalized.
- Not optional for important images: Leaving alt text empty on informative images hurts accessibility and image understanding.
Quick start
- Describe the image accurately and concisely (under 125 characters).
- Include relevant keywords naturally, if they fit the description.
- Use empty alt (
alt="") for purely decorative images. - Avoid phrases like "image of" or "picture of" — screen readers already announce it as an image.
- Test with a screen reader or by disabling images in your browser.
Common mistakes
- Keyword stuffing: Writing
alt="buy cheap apples online"instead of describing the image. - Leaving alt text empty on important images (e.g., product photos, infographics).
- Using vague text:
alt="image",alt="photo", oralt="graphic". - Treating alt text as a caption: Alt text should not repeat surrounding text or be a long description.
Next step
FAQ
What is the difference between alt text and title attribute?
Alt text provides a textual alternative for images when they cannot be displayed, while the title attribute offers additional information as a tooltip. Alt text is essential for accessibility; title is optional.
Related topics
Sources
- Google Search Central — Best source for Google's guidance on image SEO and how Google interprets image text.
- W3C WAI — Authoritative accessibility guidance on alternative text and non-text content.
- MDN Web Docs — Clear technical reference for the HTML `alt` attribute and proper usage.
Reviewed by Lucía Marín, Founding editor.