It is important that all images used as links clearly describe the content target of the link in ALT text. Linked images are often devoid of contextual information that would indicate a likely link target. This makes the user's search for information less efficient and can be a significant problem for those with low connection speeds or speech/braille browsers.
Linked images should have ALT text that describes the target content of the link. Providing a TITLE attribute is also useful because many visual browsers will display this when the mouse is "hovered" over the image. An acceptable text equivalent can often be considered as an acceptable descriptive title for the linked resource.
Example of an Inaccessible Linked Image
This example image is one of a series of linked images on the homepage of the University of Illinois. It features a new campus building and it links to a page with information about the recent growth of the university.
The provided ALT text, "always growing," is not a great text equivalent because it does not clearly suggest where the link will take the user. Without title text, even users with graphical browsers must guess at the link's target content.
Example of an Accessible Linked Image
Better ALT text is, "Recent University Growth". If the text "Always Growing" was associated with a marketing campaign, the ALT text could include this marketing content: "Always Growing: Recent University Growth".
alt="Recent University Growth"
title="Recent University Growth" />