Why the Alt Attribute May Be Omitted
alt attribute was recently worked on to thoroughly
improve its definition, including an in depth explanation of how to provide
appropriate alternate text, with clear authoring requirements.
The requirements describe situations where alternate text must be provided,
where an empty
alt attribute must be used and, most controversially,
alt attribute may be omitted entirely. This
is controversial because at first glance, it seems like an attempt to endorse
the bad and inaccessible practice of omitting the
and thus yet another slap in the face for accessibility. That is an unfortunate
misconception that needs to be carefully examined to settle any concerns people
have. Although it may seem backwards, the situation is actually much more
There are many observed cases where alternate text is simply unavailable and there’s little that can be done about it. For example, most users of photo sharing sites like Flickr wouldn’t have a clue how or why to provide alternate text, even if Flickr provided the ability. While everyone agrees that it would be wonderful if all users did – indeed, the spec strongly encourages that – most users simply won’t.
The problem being addressed is what should be done in those cases where no
has been provided and is virtually impossible to acquire. With the current
requirement for including the
alt attribute in HTML4, it has been
observed that many systems will attempt to fulfil the requirement by generating
alternate text from the images metadata.
Flickr, for example, repeats the images title; Photobucket appears to combine the image’s filename, title and the author’s username; and Wikipedia redundantly repeats the image caption. The problem with these approaches is that using such values does not provide any additional or useful information about the image and, in some cases, this is worse than providing no alternate text at all.
The benefit of requiring the
alt attribute to be omitted, rather
than simply requiring the empty value, is that it makes a clear distinction
between an image that has no alternate text (such as an iconic or graphical
representation of the surrounding text) and an image that is a critical part
of the content, but for which not
alt text is available. It has
been claimed that Lynx and Opera already use this distinction.
For images without
alt attributes Lynx shows the filename and
Opera displays "Image", but neither show anything for images with empty
It is still somewhat questionable whether this distinction is actually useful
and whether or not browsers can realistically make such a distinction with
real world content, and that is certainly open to debate if you have further
evidence to provide.
It has been suggested that taking away the unconditional requirement for the
will affect the ability of validators to notify authors of their mistakes and
take away a useful tool for promoting accessibility. However, using validation
errors as an accessibility evangelism tool is not necessarily the only, nor
the best, way to address the issue.
While it is indeed very useful for authors to know when they have mistakenly
alt attribute, attempting to unconditionally enforce
their use, using a tool as blunt as a validator, is counter productive since
it encourages the use of poor quality, automatically generated text. Besides,
nothing will prevent conformance checkers and authoring tools from notifying
authors, if they so desire.
No practical accessibility benefits are lost by conceding the fact that you
cannot force everyone to provide alternate text and making the alt attribute
optional for the purpose of document conformance. No-one is claiming that conformance
to HTML5 equates to conformance with accessibility requirements. There are
lots of things that are considered technically conforming in HTML, yet still
inaccessible if used poorly. Making alt technically optional doesn't stand
in the way of accessibility requirements, nor greatly impact upon accessibility
evangelism. It just acknowledges the reality of the situation in the hope of
reducing the prevalence of poor quality, automatically generated