Images are of practically no use to blind users. It is important to provide associated alt text with the image that appropriately describes the image. The alt text must not describe the image only but it should also provide the same user experience. For instance, alt text for an image of the “world” icon, used for notifications on Facebook, should read “notifications” rather than “world” or “planet earth”.
The alt text for an image is read out by screen readers, so images used for decorative purposes should almost always be include as backrounds in CSS or else have a null or empty value for their alt attribute, which will instruct the screen reader to ignore the image.
