Direct from w3 org
Success Criterion 1.1.1 Non-text Content
Understanding Non-text Content|
How to Meet Non-text Content
(Level A)
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. (Refer to
Success Criterion 4.1.2 for additional requirements for controls and content that accepts user input.)
Time-Based Media
If non-text content is time-based media, then text alternatives at least provide descriptive identification of the non-text content. (Refer to
Guideline 1.2 for additional requirements for media.)
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 technology.