This image is used as a border in the page design and has a purely
decorative purpose.
Screen readers also allow the use of WAI-ARIA to hide elements by using role="presentation". However, currently, this feature is not as widely supported as using a null alt attribute.
Example 2: Decorative image as part of a text link
This illustration of a crocus bulb is used to make the link easier to identify and to increase the clickable area but doesn’t add to the information already provided in the adjacent link text (of the same anchor). In this case, use a null (empty) alt value for the image.
Example 3: Image with adjacent text alternative
This picture of a sleeping dog is already sufficiently described by the adjacent text. There is no need to repeat this information, and a null (empty) alt value can be used for this image.
Example 4: Image used for ambiance (eye-candy)
This image is used only to add ambiance or visual interest to the page.