Alternative text, or “alt text,” is a written description of an image for individuals who are blind or visually impaired and use screen readers. When a screen reader encounters an image, it reads the alt text aloud so the user can understand the content and purpose of that image.
Any image that contributes to the meaning of your content must include descriptive alt text. This includes:
- Infographics that explain concepts in a lecture
- Charts or graphs presenting data
- Campus event flyers posted on a webpage
- Images that provide instructional context
Key principles for writing accurate alternative text
- Be concise: Alt text should be one to two sentences and no more than 125 characters.
- Be descriptive: Aim to convey the same content and purpose of the image through your alt text.
- Focus on context: Explain why the image is important and how it connects to the surrounding text, since the same image may require different alt text in different contexts.
- Avoid vague phrases: Screen readers already announce that content is an image, so phrases such as “picture of” or “image of” are unnecessary.
- Avoid redundancy: Don’t use alt text to repeat information that is already shared in the caption or the text immediately surrounding the image.
- Describe functionality: If an image is a button (such as “Submit Document”), the alt text should describe its action, not its appearance.
If an image is used only for decorative purposes (for example, a divider line or a stylish border) and contributes no information to the context, it should be marked as decorative rather than given alt text. Most platforms let you do this by checking a “Decorative” box in the alt text settings when remediating a file for accessibility.
Note: In Google Workspace, select “Mark As Artifact” to mark an image as decorative.
For more information, see WebAIM's Alternative Text guide.
Still need help? Submit a Help Ticket to the Office of OneIT College Support at https://services.help.charlotte.edu/