What Is Alt Text and How Should You Write It for SEO and Accessibility?
Alt text is the text alternative provided through an image’s HTML alt attribute. It should communicate the image’s purpose or essential information to people who cannot see it and provide context when the image does not load. Search engines may also use it to understand images, but accessibility and meaning should come before keyword optimization.
Images can make a page easier to understand, but only when their meaning is available to people who cannot see them.
Alt text provides that alternative. It supports accessibility, appears when an image cannot load, and gives search engines context about visual content.
The correct term is the alt attribute, although “alt tag” is commonly used.
1. What is alt text?
Alt text is the text value inside an image element’s HTML alt attribute:
<img src="black-running-shoe.jpg" alt="Black men’s running shoe viewed from the side">
Assistive technology can announce this text when the image conveys information. Browsers may show it when the image fails to load. Search engines may use it with the surrounding page context to understand the image.
2. Alt text, captions, filenames, and title attributes
- Alt text provides an equivalent for the image’s purpose or information.
- A caption is visible content that adds context for everyone.
- The filename can help with asset organization and image context.
- The title attribute may create a tooltip but is not a substitute for alt text.
These elements can support one another, but they serve different functions.
3. Why alt text matters
3.1 Accessibility comes first
A screen-reader user needs access to the information or function that a visual provides.
Without a useful alternative, a product image, chart, instructional screenshot, or image-based control may become incomplete or unusable.
3.2 It provides a fallback
If a file is missing, blocked, or slow to load, alt text can preserve the essential meaning instead of leaving an empty space.
3.3 It helps image understanding and search
Search engines evaluate the image, filename, surrounding text, page topic, links, and other signals. Descriptive alt text can improve understanding and may support visibility in image results.
It is a supporting signal, not a shortcut to rankings.
4. Decide what the image does in context
The same image may need different alt text on different pages. Describe its purpose in the current context, not every visible detail.
4.1 Informative images
Describe the information that the reader would miss.
Example:
alt="Dashboard showing a 24% increase in qualified leads from organic search"
4.2 Decorative images
If the image adds no information and exists only for visual styling, use an empty alt attribute:
alt=""
This allows assistive technology to skip it. Omitting the attribute entirely can cause some tools to announce the filename.
4.3 Functional images and linked images
When an image acts as a link or control, describe the destination or action rather than its appearance.
For a logo linked to the homepage, “Seven Gold Agency home” is more useful than “black and gold logo.”
4.4 Images containing text
Avoid placing essential copy only inside an image. When it cannot be avoided, the text alternative should communicate the essential wording and purpose.
4.5 Charts and complex diagrams
A short alt text should identify the chart and its main takeaway. Provide the full data or longer explanation in nearby text, a table, or a dedicated description.
Trying to place an entire data analysis inside one alt attribute creates a poor experience.
5. How to write useful alt text
- Determine why the image is present.
- Communicate the information or function a user would otherwise miss.
- Use specific, natural language.
- Keep it concise without removing essential context.
- Include a relevant keyword only when it genuinely describes the image.
Most descriptions do not need phrases such as “image of” or “picture of.” Assistive technology already identifies the element as an image. Mention the medium only when it matters, such as a screenshot, diagram, map, painting, or photograph.
6. Alt text examples
Product image
Weak: alt="shoe"
Better: alt="Women’s white leather low-top sneaker"
Team photograph
Weak: alt="team"
Better: alt="Seven Gold strategy team during a client workshop"
Instructional screenshot
Weak: alt="screenshot"
Better: alt="Google Search Console performance report with the Queries tab selected"
Decorative gradient
Correct: alt=""
7. Common mistakes
- Leaving informative images without an alt attribute.
- Using the filename as the description.
- Repeating the same alt text across every image.
- Stuffing keywords that do not describe the image.
- Describing decorative visuals that should be ignored.
- Repeating a caption word for word when it adds no value.
- Writing a long paragraph for a simple image.
- Using alt text to hide unrelated SEO copy.
8. How to audit alt text at scale
A crawl can identify missing and empty alt attributes, but automation cannot always decide whether the image is informative, decorative, or functional.
Prioritize:
- Product and category images.
- Linked images and image-based controls.
- Charts, diagrams, and screenshots.
- Images on high-traffic landing pages.
- Templates that repeat the same problem across many URLs.
Combine automated reporting with a manual accessibility review of context and behavior.
9. Where alt text fits in SEO
Alt text is one part of a complete SEO strategy. Image quality, compression, dimensions, responsive delivery, filenames, surrounding content, structured data where relevant, and page performance also matter.
Write alt text for the person who needs the image’s meaning. When that description is accurate and relevant, search engines benefit too.
Continue improving the website
Use these guides to connect structure, accessibility, conversion, and discoverability.
Images can make a page easier to understand, but only when their meaning is available to people who cannot see them.
Alt text provides that alternative. It supports accessibility, appears when an image cannot load, and gives search engines context about visual content.
The correct term is the alt attribute, although “alt tag” is commonly used.
1. What is alt text?
Alt text is the text value inside an image element’s HTML alt attribute:
<img src="black-running-shoe.jpg" alt="Black men’s running shoe viewed from the side">
Assistive technology can announce this text when the image conveys information. Browsers may show it when the image fails to load. Search engines may use it with the surrounding page context to understand the image.
2. Alt text, captions, filenames, and title attributes
- Alt text provides an equivalent for the image’s purpose or information.
- A caption is visible content that adds context for everyone.
- The filename can help with asset organization and image context.
- The title attribute may create a tooltip but is not a substitute for alt text.
These elements can support one another, but they serve different functions.
3. Why alt text matters
3.1 Accessibility comes first
A screen-reader user needs access to the information or function that a visual provides.
Without a useful alternative, a product image, chart, instructional screenshot, or image-based control may become incomplete or unusable.
3.2 It provides a fallback
If a file is missing, blocked, or slow to load, alt text can preserve the essential meaning instead of leaving an empty space.
3.3 It helps image understanding and search
Search engines evaluate the image, filename, surrounding text, page topic, links, and other signals. Descriptive alt text can improve understanding and may support visibility in image results.
It is a supporting signal, not a shortcut to rankings.
4. Decide what the image does in context
The same image may need different alt text on different pages. Describe its purpose in the current context, not every visible detail.
4.1 Informative images
Describe the information that the reader would miss.
Example:
alt="Dashboard showing a 24% increase in qualified leads from organic search"
4.2 Decorative images
If the image adds no information and exists only for visual styling, use an empty alt attribute:
alt=""
This allows assistive technology to skip it. Omitting the attribute entirely can cause some tools to announce the filename.
4.3 Functional images and linked images
When an image acts as a link or control, describe the destination or action rather than its appearance.
For a logo linked to the homepage, “Seven Gold Agency home” is more useful than “black and gold logo.”
4.4 Images containing text
Avoid placing essential copy only inside an image. When it cannot be avoided, the text alternative should communicate the essential wording and purpose.
4.5 Charts and complex diagrams
A short alt text should identify the chart and its main takeaway. Provide the full data or longer explanation in nearby text, a table, or a dedicated description.
Trying to place an entire data analysis inside one alt attribute creates a poor experience.
5. How to write useful alt text
- Determine why the image is present.
- Communicate the information or function a user would otherwise miss.
- Use specific, natural language.
- Keep it concise without removing essential context.
- Include a relevant keyword only when it genuinely describes the image.
Most descriptions do not need phrases such as “image of” or “picture of.” Assistive technology already identifies the element as an image. Mention the medium only when it matters, such as a screenshot, diagram, map, painting, or photograph.
6. Alt text examples
Product image
Weak: alt="shoe"
Better: alt="Women’s white leather low-top sneaker"
Team photograph
Weak: alt="team"
Better: alt="Seven Gold strategy team during a client workshop"
Instructional screenshot
Weak: alt="screenshot"
Better: alt="Google Search Console performance report with the Queries tab selected"
Decorative gradient
Correct: alt=""
7. Common mistakes
- Leaving informative images without an alt attribute.
- Using the filename as the description.
- Repeating the same alt text across every image.
- Stuffing keywords that do not describe the image.
- Describing decorative visuals that should be ignored.
- Repeating a caption word for word when it adds no value.
- Writing a long paragraph for a simple image.
- Using alt text to hide unrelated SEO copy.
8. How to audit alt text at scale
A crawl can identify missing and empty alt attributes, but automation cannot always decide whether the image is informative, decorative, or functional.
Prioritize:
- Product and category images.
- Linked images and image-based controls.
- Charts, diagrams, and screenshots.
- Images on high-traffic landing pages.
- Templates that repeat the same problem across many URLs.
Combine automated reporting with a manual accessibility review of context and behavior.
9. Where alt text fits in SEO
Alt text is one part of a complete SEO strategy. Image quality, compression, dimensions, responsive delivery, filenames, surrounding content, structured data where relevant, and page performance also matter.
Write alt text for the person who needs the image’s meaning. When that description is accurate and relevant, search engines benefit too.
Continue improving the website
Use these guides to connect structure, accessibility, conversion, and discoverability.
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Summary
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FAQ
No. Informative and functional images need a meaningful text alternative. Purely decorative images should normally use an empty alt attribute, alt="", so assistive technology can ignore them. The decision depends on the image’s purpose in context.
There is no universal word limit. Use the shortest description that communicates the image’s relevant purpose or information. A simple image may need only a few words, while a complex chart may require a short alt text plus a longer explanation nearby.
Alt text can help search engines understand an image and may support visibility in image search, but it is only one signal. It does not replace strong page content, useful images, descriptive filenames, technical accessibility, and a coherent SEO strategy.
