How to Write Useful Alt Text for Images

Alt text communicates purpose, not every pixel

Alternative text replaces the information or function an image contributes when the image cannot be seen. Good alt text depends on context. The same photo might need “Red running shoe with white sole” on a product page, a description of tread wear in a support guide, or empty alt text when it merely repeats nearby decoration.

A practical writing method

1. Ask why the image is on this page.
2. Identify the information a reader would miss without it.
3. Describe that information in the fewest natural words that do the job.
4. Include visible text only when it matters and is not already adjacent.
5. For a linked image, describe the destination or action.
6. Read the paragraph and alt text together to remove repetition.

Avoid starting every description with “image of” or “picture of.” Screen readers already announce that the element is an image. Mention the medium when it is meaningful, such as “diagram,” “screenshot,” or “watercolor.”

Examples by context

Use AI as a draft, not the final authority

An image-description tool can identify objects and propose captions, but it does not automatically know why the image appears on your page. Review names, numbers, relationships, identity claims, and sensitive inferences. Then rewrite the draft for the page’s purpose.

AI Image Describer can generate captions, descriptions, prompts, and alt-text drafts from images. The human publishing the page remains responsible for accuracy and context.

Common mistakes

• Stuffing search keywords that do not help someone understand the image.
• Repeating the caption or adjacent paragraph word for word.
• Describing decorative imagery that should be skipped.
• Omitting the action of an icon-only link or button.
• Using an AI-generated description without checking visible text and factual details.

Common questions