Alternative Text for Images in Documents

What is alt text?

Alt text (alternative text) is a short, descriptive text that explains what an image shows. It helps users who cannot see the image - whether due to blindness, low vision, or slow internet connections. Alt text is read aloud by screen readers and appears if images fail to load. Good alt text conveys the purpose and content of images, ensuring everyone can access the information. It also helps with search engine optimization and usability.

Informative images

Informative images convey essential content or functionality that users need to understand the document. These images require descriptive alt text that explains their purpose and content. Examples include:

• Charts, graphs, and data visualizations
• Diagrams and illustrations that explain concepts
• Screenshots showing software interfaces or processes
• Maps and floor plans
• Product images in catalogs

Decorative images

If an image adds no information, mark it decorative so it’s skipped by screen readers. In authoring tools, use “Mark as decorative.” These are images used purely for visual appeal or design purposes that don't convey essential information. Unlike informative images, decorative images should be ignored by screen readers to avoid unnecessary interruptions.

Logos

Logos that serve a function (brand identification) typically should not be marked decorative in formal templates. Provide appropriate alt text describing their purpose.

How to write good alt text

• Describe essential information or function, in under ~125 characters (with spaces).
• Don’t start with “Image of …” — screen readers already announce images.
• For charts and graphs, summarize key trends or data points.
• Use plain language and avoid jargon or abbreviations unless explained.
• Alt Text References: When surrounding text/captions fully convey an image's content, alt text can be shorter and refer to more information in another location.

Adding alt text: Step-by-Step

Follow these steps to add alt text to images in your documents:

1. Right-click on the image
2. Choose Edit Alt Text from the context menu
3. In the Alt Text pane that appears on the right:
   • Type a brief, clear description in the text box
   • Keep it under 125 characters (with spaces)
   • For tables/charts/graphs, summarize the key data or trend
   • Focus on the image object's purpose or key information
4. If the image is purely decorative, check Mark as decorative
5. Click outside the pane or press Enter to save