Alternative text, or “alt text,” is a written description of the visual content in an image. It is typically one or two sentences long and should convey any important visual information.

Alt text is important because it allows images and their critical information to be conveyed to visually impaired individuals and screen reader users.

Alt text is a “behind-the-scenes” description of an image. It’s not typically visible in a document or webpage; it is available to people using a screen reader to provide them access to the same content.

How to write alt text

The key to writing succinct alt text is to ask yourself why the image is important in the context of the document or webpage. Let that guide your decision on what details to include. It is best to put the most important information at the beginning of the alt text and avoid starting alt text with phrases like "image of" or "photo of" as it is repetitive since screen reading software announces this information. Lastly, avoid providing subjective interpretation; just describe what is visually presented in a neutral tone.

Creating or editing alt text in Microsoft Word (.docx files)

1. Select the image then select the Alt Text option under the Picture Format toolbar.

2. Describe the image in 1-2 sentences.

Creating/editing alt text in Adobe Acrobat (.pdf files)

1. In Adobe Acrobat, select Accessibility from the right-hand toolbar.

2. Click Reading Order.

3. Draw a rectangle around the image and select the Figure option in the Reading Order window to define the image. The figure’s textbox will say No alternate text exists if done properly.

4. Right-click on the defined image and select Edit Alternate Text.

5. Describe the image in 1-2 sentences and select OK to save your edits.

6. The alt text will now appear alongside the defined image in Accessibility mode.

Additional Resources

• Identity and Inclusion in Alt Text from CU Boulder’s Digital Accessibility Office
• A Decision Tree to determine whether alt text is needed from W3C
• Alt Text vs. Image Descriptions from Accessible Social
• Articles on Alt Text from WebAIM