Accessibility Standards (WCAG)
Key Concepts
- Perceivable
- Operable
- Understandable
- Robust
Perceivable
Perceivable information and user interface components must be presentable to users in ways they can perceive. This means that users must be able to perceive the information being presented (it can't be invisible to all of their senses).
Example:
Providing text alternatives for non-text content, such as images, ensures that users who cannot see the images can still understand the content.
Operable
User interface components and navigation must be operable. This means that users must be able to operate the interface (the interface cannot require interaction that a user cannot perform).
Example:
Ensuring that all interactive elements are keyboard accessible allows users who cannot use a mouse to interact with the website.
Understandable
Information and the operation of user interface must be understandable. This means that users must be able to understand the information as well as the operation of the user interface (the content or operation cannot be beyond their understanding).
Example:
Using clear and simple language in error messages helps users understand what went wrong and how to fix it.
Robust
Content must be robust enough that it can be interpreted reliably by a wide variety of user agents, including assistive technologies. This means that as technologies and user agents evolve, the content should remain accessible.
Example:
Using semantic HTML ensures that the content is structured in a way that can be interpreted by assistive technologies, such as screen readers.
Examples and Analogies
Perceivable Example
Think of a book with illustrations. If the illustrations are not described in the text, a blind reader would miss out on the full story. Providing descriptions ensures everyone can perceive the content.
Operable Example
Consider a door with a handle. If the handle is too high for a person in a wheelchair to reach, they cannot operate the door. Making the handle accessible ensures everyone can operate it.
Understandable Example
Imagine a recipe written in a foreign language. If you don't understand the language, you won't know how to prepare the dish. Using clear language ensures everyone can understand the instructions.
Robust Example
Think of a building with a universal design. It remains accessible to people with different needs, even as new technologies and methods of access are developed.