A "long description" in alternative text (alt text) refers to additional information provided for an image or other non-text content that requires a more detailed explanation. Alt text is a brief text alternative to describe the content and function of an image, and it's required in order to make web content accessible to people with visual impairments who use screen readers. 

However, there are instances where the content and context of an image are complex, and a brief alt text may not be sufficient. In such cases, a "long description" provides more extensive information. This additional description is often placed elsewhere on the webpage and linked from the short alt text. Users can choose to access the long description if they need more detailed information about the image. 

Including long descriptions enhances the accessibility of web content by ensuring that people with visual impairments can access the same level of information and context as sighted users. It aligns with the principle of providing equivalent alternatives for non-text content, as outlined in Web Content Accessibility Guidelines (WCAG).

To add the long description to an image,

  1. From the edit page view, go to the image you want to add the long description to, click on the image and then click Editcomplex graphic of the ADDIE Model
  2. The Edit Image form will appear. Click the Long Description tab.
    The Edit Image form will Long Description tab hidden
  3. Complete the Link Title and Image Description fields and save changes to the block.
    Long Description tab with title and image description fields
  4. The image will now appear with an accessible link to a long description/transcript.
    image with an accessible transcript linksample accessible transcript for a long description