Accessibility Metadata

Structured information that describes the accessibility features, hazards, or access modes of digital content. Accessibility metadata can be embedded within content (such as alt text in HTML) or stored externally in separate databases or annotation systems. External accessibility metadata enables third parties to enhance content accessibility without modifying the original source, as in crowdsourced labeling systems or accessibility overlays. Standards like Schema.org accessibility properties and EPUB Accessibility metadata provide vocabularies for describing whether content is compatible with assistive technologies, contains hazards like flashing, or provides alternatives like audio descriptions and captions.