A Brief Introduction to Using Alt Text

A few easy dos and don’ts for increasing image accessibility

Twitter recently increased the prominence of the alt text option for images and GIFs.  With the new roll-out of the “ALT badge” and better image accessibility features, many questions about alt text and how to use it remain.

Alt text is the shortened version of “alternative text” and focuses on the text that is read aloud by a screen reader when encountered on the webpage, document, or site.  Other terms for this are “alt tag,” “alt attribute,” or “image description.”

Overall, the goal of Alt Text is to “convey the ‘why’ of the image” with respect to the context in which it is presented.  Often, images present essential information.  These might be infographics, maps, graphs/charts, or other context-dependent essential information.  The goal is to have well-written, descriptive alt text in order to reduce ambiguity.

For Twitter, “ALT” is the abbreviation for alternative text, which is the technical name for image description.

Dos

• Keep the description short.  This might be a few words or infrequently a sentence or two.

• Avoid unnecessary words like “image of” or “photo of” in the description

• Focus on the content of the image (for example, the essential information needed from the graph, not simply that it is a graph)

• Create alt text for videos when needed

• Consider using more detailed captions to discuss figures, rather than lengthy alt text

Don’ts

• Write alt text for decorative, meaningless images (instead, mark these images as decorative)

• Describe only the superficial surface features

• Repeat the same alt text everywhere for the same image

• Use the filename

• Duplicate descriptions if it is already included in the main text

Twitter provides additional guidance on setting image descriptions, including options for web, Android, and Apple, as well as using VoiceOver, JAWS, and NVDA.  JAWS, NVDA, and Microsoft Narrator are screen readers that will read aloud the added alt text descriptions.  Microsoft also has guidance on introducing alt text, as well as examples, in their software products.  Interestingly, Microsoft 365 has the ability to generate alt text automatically.  Naturally, it seems like this would need to be checked for accuracy.

Whether it is social media or other uses, opportunities to improve accessibility through alt text abound.  The keys are following best practices and learning how each platform, program, or site adds alt text to images, figures, graphics, videos, and more.