Principle 1
Perceivable
Users must be able to perceive the content of apps. For example, someone who is blind cannot see the interface. Deaf users cannot hear information. Ensure that information is perceivable in an alternative way for users with disabilities.
Examples
When an image or graph is not described textually, users with a visual impairment cannot perceive the information.
When a video does not have captions, users with a hearing impairment cannot understand the information.
When a button has too low contrast, it might not be clear for users that it can be clicked.
When a form does not have clear labels, it can be unclear to users where and what information is expected from them.