Alt text helps people who cannot see images by briefly describing the image’s content. This makes websites and documents accessible to everyone—for example, to blind users who use a screen reader to have the page read aloud.
Stick to the main message
Convey all the important information in the image (with infographics, this can often be a lot; in such cases, it’s worth providing the complete data additionally as text or a table)
Don’t describe every detail; the key message is what matters
Keep it brief
Avoid redundancy with the surrounding text
“As brief as possible, as detailed as necessary.”
Guideline: 80–100 characters (not always possible for complex images)
Write as you would describe it verbally
Fluid and natural language
No stringing together of keywords (So NOT: “Sarah, garage, customer, car,” but rather: “Sarah is standing in a garage next to a car and talking to a customer.”).
Period at the end of the sentence. This creates a brief pause in the voice output.
Avoid introductory phrases like “An image of…” or “In this image…”. The screen reader automatically announces that it is an image.
Convey the mood as well
If the image conveys a specific atmosphere, emotion, or mood, describe it.
Emojis, links, or quotation marks do NOT belong in the alt text
Best practice is not to include alt text for every image.
No alt text for decorative images: Only if an illustration or image contains information that goes beyond mere decoration should it receive alt text (example of a decorative image: The main character of the learning module smiles at the learner but is not mentioned in the text.)
Check relevance: Conveys only the most important information.
Keep it concise: As short as possible, as long as necessary.
Language: Fluent, natural—no stringing together of keywords.
Tone & Context: Include important emotions or actions.
Avoid repetition: No phrases like “Image of …”.
Complex graphics: Provide additional text or links for infographics or other complex images.