Long description provides a text version of information provided in a detailed or complex image. You may already be familiar with simple alternative text, which provides brief descriptions of visual content. But when an image is detailed and complex, simple alternative text isn’t sufficient to capture its meaning.
Enter long description. Long description can be used in many different contexts, but most commonly, creators use long description when they are making content they expect users to learn from. This instructional content frequently includes diagrams, charts, and graphs. Long description details the complex information that learners are expected to know about the image.
Because long description is rather lengthy and detailed, it can’t be put into alt text fields. Instead, you’ll need to decide where to put it. You have two options:
- Describe the image in the surrounding text. Screen readers will benefit from this placement, but so will other readers as well.
- If your space is limited, you can create an appendix that contains the long description. If you go with this option, make sure you link from the original location to the appendix AND link from the appendix to the original text. That way, users can easily navigate back and forth between the original text and image and the description.
Even though your long description provides the actual description of the image, you still need to alert screen readers to the image. You also need to ensure that users can make the connections between the image in the original location and the long description. To do that, you need to include a very brief snippet of alt-text for the image. This alt-text should clearly relate to both the image and the long description. Check out the example below that shows how to make the connection:
- Alt Text: “Chart 1.2”
- Long Description: “Chart 1.2 suggests that…”
Long Text Example
Open Suny: https://www.youtube.com/watch?v=9d_H78ZDQJU&t=42s