Alt text (alternative text) is a metadata field that contains a concise written description of an image, enabling screen readers to communicate visual content to blind and low-vision users. It exists separately from visible captions or file names and must convey both the content and function of an image in context. Unlike a general image description, alt text answers what information this specific image provides to the page or document where it appears.
Why it matters
Missing or poorly written alt text creates legal liability under accessibility laws like the ADA and Section 508, exposes organizations to discrimination lawsuits, and excludes customers with disabilities from accessing product information or brand content. When images fail to load due to network issues or browser errors, alt text provides the only indication of what users are missing, directly affecting conversion rates and user experience.
How it shows up in practice
A healthcare system's patient education team publishes a post-surgery care guide with anatomical diagrams. Their DAM enforces controlled vocabulary for alt text fields, requiring writers to include body part names, directional terms, and procedural context rather than generic phrases like "diagram of knee." When the guide is exported to their patient portal CMS, screen readers accurately convey "anterior view of right knee showing incision location for ACL repair," enabling visually impaired patients to understand post-operative wound care instructions.
Common mistakes
- Writing alt text that duplicates visible captions instead of describing the image itself, forcing screen reader users to hear redundant information.
- Storing alt text in file names or separate spreadsheets rather than embedded metadata fields, breaking the connection when assets move between systems.
- Using identical alt text across translated versions of assets without adapting descriptions to cultural context or region-specific visual references.