What alt text does

Alt text gives an image a text alternative when the image communicates information or performs a function. It helps people using screen readers, people with images turned off, and teams reviewing content quality.

When images need alt text

Use descriptive alt text when the image adds information that is not already available nearby. Product photos, service photos, staff images, charts, infographics, event photos, notices, screenshots, and linked images often need careful wording.

When empty alt is appropriate

Use alt="" when an image is truly decorative, redundant, or already described by adjacent text. Empty alt is not a shortcut for hard images. If the image is a link, button, chart, notice, or primary content, review it carefully before leaving it empty.

Practical examples

  • Product or service images: describe the product, service, or visible detail that helps the user understand the offer.
  • Linked images: describe the link destination or action, such as "Book a roof repair consultation", not just "roof photo".
  • Team photos: use names and roles when that information is not already visible; avoid vague text like "staff".
  • Charts and infographics: give the main takeaway in alt text and provide detailed data in nearby text or a table.
  • Logos: usually use the organization or product name. If the logo links home and the link already has a clear label, the image can sometimes be empty.

Common mistakes

  • Missing the alt attribute entirely.
  • Using file names such as IMG_1234.jpg, DSC0001, or screenshot-2024-01-01.png.
  • Using generic labels such as image, photo, graphic, banner, screenshot, or logo.
  • Copying the same alt text across unique product, staff, or gallery images.
  • Describing a linked image visually instead of naming where the link goes.
  • Writing a long visual inventory when a short contextual description would help more.

What automated tools can catch

The alt text checker can flag missing attributes, empty alt text, linked images with weak names, filename-like alt text, generic terms, and repeated descriptions. The full website accessibility checker includes image findings in page reports.

What still needs human review

Automation cannot prove that alt text is meaningful in context. A person still needs to decide whether the image is informative, functional, decorative, or redundant; whether surrounding text already says the same thing; and whether complex images need longer text alternatives.

Workflow for editors and agencies

  1. Review images page-by-page before publishing.
  2. Use the alt text review checklist to decide which images need descriptions.
  3. Run the alt text checker on pasted HTML for quick pattern checks.
  4. Compare uncertain cases with the alt text examples.
  5. For broader launch review, use the Canadian website accessibility checklist.

Related issue guidance

For related guidance, see what automated accessibility checkers miss and website accessibility for content editors.

Recommended next steps

Check your alt text Paste HTML and classify image alternatives. See alt text examples Compare bad, better, and best patterns. Open the checklist Use the print-friendly review workflow.