A long description is a way to provide long alternative text for non-text elements, such as images. Generally, alternative text exceeding 250 characters, which cannot be made more concise without making it less descriptive or meaningful, should have a long description.
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 not sufficient.
Combined with the short text alternative, the long description should be able to substitute for the non-text content.
