Use of the longdesc attribute, to point to a page with a long description of an image:
The <img> longdesc attribute is not supported in HTML5.
The longdesc attribute specifies a URL to a page that contains a long description of an image.
Tip: The longdesc attribute is so poorly supported that it should not be used. To offer a long description of an image, simply create a link (that is visible to anyone) to a page with the description.
|longdesc||Not supported||Not supported||Not supported||Not supported||Not supported|
|URL||A URL to a page that describes the image.