Long description
A longer form of alternative text for non-text elements that should be able to serve as a full substitution for the non-text content it describes.
Why it matters
The objective of this technique is to provide a long text alternative that serves the same purpose and presents the same information as the original non-text content when a short text alternative is insufficient.
Combined with the short text alternative, the long description should be able to substitute for the non-text content. The short alternative identifies the non-text content; the long alternative provides the information.
If the non-text content were removed from the page and substituted with short and long descriptions, the page would still provide the same function and information.
In deciding what should be in the text alternatives, the following questions are helpful.