longdesc Attribute

Where to use the longdesc Attribute

• As Type URI:
  longdesc is declared on the element: img

Description

The longdesc attribute of an img element is used to specify a URI to a document containing a long description of the image, which should aim to expand upon the alternative text specified in the alt attribute.

Having said that, it appears that the longdesc attribute is very poorly supported by the majority of user agents (even assistive technologies) so if the content of an image is integral to the meaning of your page (and can't be described briefly using an alt attribute) it's always best to include a separate, visible link (using the a element) to the full description of the image.

Relative URIs in longdesc attributes are resolved with respect to the current document's base URI (see the base element).