Validator.nu alt advice
The purpose of this page is to enable collaborative creation of advisory text for certain cases of
alt usage so that this advice can be displayed by Validator.nu. Note that like the rest of this wiki, editing requires you to agree to release your contributions under the MIT license (see wiki footer). Please note that while copying text from the WHATWG version of HTML 5 is OK, copying text from RFCs or W3C specs is not OK.
img elements of the page (if any) are shown below categorized by their type of textual alternative. Please review that the images in the group match the definition all what kind of images should appear in that group.
The following images are not links and have no textual alternative available (no
alt attribute), and are, therefore, not accessible to people who cannot see the images or understand the symbols in them.
An image belongs here if the image is significant (non-decorative) and the markup generator doesn’t have knowledge on what the image is about available. For example, a photo gallery generator does not have textual alternatives available when the user refuses to provide them.
Purely decorative images should have the empty string as the textual alternative (
alt=""), so it is a mistake for those to appear here. Also, when the markup writer knows what the images are about, (s)he should write textual alternatives.
The following images are links and have no textual alternative available (no
alt attribute). Having an
img element without a textual alternative as the content of a link is handled ungracefully by popular screen readers.
Omitted from non-graphical presentation
The following images are marked to be omitted from non-graphical presentations (
Purely decorative images belong in this category. Also, iconic images that are redundant with text next to them belong here.
If the page would become less understandable if the presence of an image was concealed, the image doesn't belong here. In that case, a textual alternative should be supplied or if the markup generator does not have a textual alternative available (because the user refused to provide it), the
alt attribute should be omitted by the markup generator.
Images with textual alternative