Accessibility Guidance for Digital Information

Important: Alt (Alternative) Text

Any time you have meaningful images or charts in a document you need to add alt (alternative) text.  Alt text is a brief description of what the image or chart shows.  This is especially important for folks who are blind or visually impaired. If someone is using screen reading software the screen reader will read the description of the image. Alt text is also helpful if the image fails to display correctly due to a lack of connectivity or software issues.

The alt text should be brief, but explain the content or purpose of the image.  Think about what you want the image to convey and use that as the basis for the alt text.

How do I determine when I should add alt text or when to leave the alt attribute empty?

Determining the appropriate alternative text for an image depends upon whether the image presents content and if the image has a function. 

• Function - Does the image contain a link? Is it a button? Is it an image map?

  1. If yes, then then image provides a function and should contain alternative text. 
  2. If no, see content below.

• Content - Does the image present content? Is there text around the image that conveys that content?

  1. If the image presents content that is not communicated by text around the image, then you must add alternative text. 
  2. If the image presents content that is communicated by text around the image, then you do not need to add alternative text.
  3. If the image does not present content and is considered decorative, then you do not need to add alternative text.