What does the robust principle in WCAG focus on?

The robust principle in the Web Content Accessibility Guidelines (WCAG) emphasizes the importance of ensuring that content is compatible with a wide range of user agents, including different web browsers and assistive technologies. This principle reflects the need for a stable and adaptable web experience, which can accommodate various ways users access information.

By focusing on compatibility with a variety of user agents, the robust principle promotes inclusivity, ensuring that all users—regardless of the tools or technologies they employ—can access web content effectively. This approach involves following established standards and best practices in web development, which helps ensure content remains accessible as technology evolves.

Other options, while relevant to web accessibility, do not encapsulate the core intent of the robust principle. For instance, ensuring information is accessible is more aligned with the perceivable principle, while improving user engagement and eliminating redundancy concern different aspects of user experience rather than the foundational compatibility that the robust principle stresses.