Benefits: Blind disabilities.
All non-text content that is presented to the user has a text alternative that serves the equivalent purpose, except for the situations listed below:
- Controls, Input: If non-text content is a control or accepts user input, then it has a name that describes its purpose.
- Time-Based Media: If non-text content is time-based media, then text alternatives at least provide descriptive identification of the non-text content.
- Test: If non-text content is a test or exercise that would be invalid if presented in text, then text alternatives at least provide descriptive identification of the non-text content.
- Sensory: If non-text content is primarily intended to create a specific sensory experience, then text alternatives at least provide descriptive identification of the non-text content.
- CAPTCHA: If the purpose of non-text content is to confirm that content is being accessed by a person rather than a computer, then text alternatives that identify and describe the purpose of the non-text content are provided, and alternative forms of CAPTCHA using output modes for different types of sensory perception are provided to accommodate different disabilities.
- Decoration, Formatting, Invisible: If non-text content is pure decoration, is used only for visual formatting, or is not presented to users, then it is implemented in a way that it can be ignored by assistive technologies.
Images can be one of the following:
- Informative: Conveys a simple concept or information that can be expressed in a short phrase or sentence.
- Functional: Initiatse interactive actions.
- Decorative: Does not add information to the content of a page, and thus the image can have null/empty alt text. Assistive technologies can ignore the image. The image may have adjacent text that sufficiently describes the image.
- Do all (non-decorative) images have alt text?
- Does the alt text provide meaningful information about the image?
- If the image is a link, does the alt text describe the link purpose?
- Are background images informational? Alt text is needed.
- Are background images decorative? Alt text is not needed.
- Can background images be hidden, but still have access to information and functionality?
Images of text
Benefits: Low vision, visual tracking problems, cognitive disabilities.
Text is used to convey information rather than images of text. Achieve desired default visual presentation, to enable people who require a particular visual presentation of text to be able to adjust the text presentation as needed.
- Is an image of text used to convey information instead of text?
- If text cannot be formatted to get the same effect as images of text.
- If the effect won't be reliably presented on the commonly available user agents.
- If using an Assistive Technologies to meet this criterion would interfere with meeting other criteria such as 1.4.4 Resize Text.
- Example - where a particular presentation of text is essential to the information being conveyed, such as type samples, logotypes, branding, etc.