Descriptive & ALT Text
Assistive technologies require a text alternative for graphics. This text is read aloud by screen readers, or it can caption the image to provide context or explanation. ALT text assists learners who have cognitive disabilities, not just those with blindness.
Remember: the role of descriptive/ALT text is to explain the image’s context or purpose to someone who can’t see or understand it! Describing the image’s content alone often does not aid learning.
- Alternative Text (WebAIM)
Provide a brief ALT description for every photo you provide to students.
Best Practices
- Don’t place captions inside the graphic; screen readers can’t read within a graphic.
- Don’t begin the caption or ALT text with “image of” or “photo of”; screen readers automatically say “image”.
- Don’t repeat the caption verbatim in ALT text; screen readers automatically say both.
- Do be concise/succinct.
- Do leave blank ALT text on decorative or background images (alt=””).
Examples
Descriptive Text in the Caption or ALT:
Painting of George Washington crossing the Delaware River. Swirling waves surround the boat where the majestic George Washington looks forward out of the storm and into the rays of light across the river as he leads his weary troops to battle. (source: WebAIM)
Descriptive Text on the Page:
George Washington faced challenges when crossing the Delaware River. Swirling waves surrounded the boat where the majestic George Washington continued forward out of the storm and into the rays of light across the river as he led his weary troops to battle.
Painting of George Washington crossing the Delaware River. Artist: Emanuel Leutze.
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