Alt all the way
Mark says that today is the most important day of his whole accessibility series, and who are we to argue? The topic is the
alt attribute for images, and the message is simple: Every image should have one, even if the image is there purely as layout decoration (in which case an empty attribute should be used). Surprisingly Mark does not give advice on chosing text for the attribute but he does provide an excellent further reading list, which includes Hixie’s superb Mini FAQ About The Alternate Text Of Images.