HTML and CSS Reference
In-Depth Information
Figure 5-9. Internet Explorer displays alt text in a
temporary pop-up window
The value for the
alt
attribute is a text string of up to 1,024 characters,
including spaces and punctuation. The string must be enclosed in quota-
tion marks. The
alt
text may contain entity references to special char-
acters, but it may not contain any other sort of markup; in particular,
style tags aren't allowed.
Graphical browsers don't normally display the
alt
attribute if the image
is available and the user has enabled picture downloading. Otherwise,
they insert the
alt
attribute's text as a label next to an image-placehold-
er icon. Well-chosen
alt
labels thereby additionally support those users
with graphical browsers who have disabled automatic image download
because of a slow connection to the Web.
Nongraphical, text-only browsers such as the ancient Lynx put the
alt
text directly into the content flow, just like any other text element. So,
when used effectively, the
alt
tag sometimes can transparently substi-
tute for missing images. (Your text-only browser users will appreciate
not being constantly reminded of their second-class web citizenship.)
For example, consider using an asterisk as the
alt
attribute alternative
to a special bullet icon:
