Alt text (or alternative text) is a description of an image that allows those who cannot see the image to access its visual information.
Why do we need alt text?
Alt text is necessary for users who rely on assistive technology such as screen readers. Screen readers are a type of software that read the content of a screen. They make it possible for people who are blind or low-vision to read and interact with digital documents, forms, and web pages. Good alt text is very important to these users, because it allows them to get the same information and experience as sighted users.
Also, if an image fails to load on a document or web page, then the alt text will be displayed in its place. This makes effective alt text very useful if users have a poor internet connection.
Writing Alt Text
Review these tips for writing good image descriptions:
- Describe the image’s relevant content and function based on its context.
- Avoid saying “image of” or “picture of”. Screen readers automatically announce images as images.
- Be concise.
- Write narratives for complex images like infographics and consider providing to ALL users.
- Avoid images of text. If you can’t avoid it, copy the text into the alternative description.
- Say something new. Don’t repeat alternative descriptions on the same page.
- Identify images as decorative if they don’t represent relevant content.
How to Add Alt Text to Images
The process for adding alt text to images varies slightly depending on the software you’re using. We’ve linked instructions for adding alt text in some common programs below.
- Blackboard by Anthology: Add Alternative Text to Images
- Microsoft Word: Add Alternative Text to a Shape, Picture, Chart, SmartArt Graphic, or Other Object
- Microsoft PowerPoint: How to Add Alt Text to an Image in PowerPoint
- Adobe Acrobat: Alt Text for Images in Adobe Acrobat (PDF)