Tips for writing effective alt-text

Now you're going back to label those few problematic images on your site. How do you know what to write? Of course, the description of an image is just as subjective a matter as the image itself, but a few suggestions will help.

• Describe the function of the image. Especially if the image is a link, "Search New Boats" is much more useful than "Photo of a powerboat."
• Brief is better. Remember, syllables are time.
• Put the most essential information first. If it is necessary to use a number of words, use "Joe’s Marine Logo: Sun rising over boat and waves" rather than "Sun rising over boat and waves: Joe’s Marine Logo."
• Meaningless graphics need not have meaningful text. If a graphic is being used as a spacer, to push other graphics into position, don't label the thing "Green spacer." Instead, put a space between the quotes of the alt-text so users don't have their train of thought disrupted by such irrelevant information. Use this "non-text" judiciously, though. If you can't think of something to say about an image, that doesn't mean it's meaningless.
• Maintain the alt-text. If your image map is rearranged so that the last item is now "Contact Us," don't forget to move the alt-text, too. Otherwise, that image will still be labeled as "Site Map" and users will be lost.
• Alt-text reflects your professionalism just as much as your choice of images. Spell words correctly.
• Make sure Alt Text is present and relevant for images on your website

Sources: American Foundation for the Blind