What does the principle of "understandable" refer to in web accessibility?

The principle of "understandable" in web accessibility emphasizes that the information presented on websites, as well as the operations of the user interface, should be clear and comprehensible to users. This means that content should be formatted in a way that enhances readability and navigability, using clear language, consistent navigation mechanisms, and logical structure.

By focusing on clarity, this principle ensures that all users, including those with disabilities, can interact with content effectively. It encompasses various aspects such as the use of headings, lists, simple language, and intuitive layouts, all aimed at facilitating understanding. Clear instructions and feedback are also essential so that users can easily comprehend what actions they need to take and what the outcomes will be.

This is distinctly different from ensuring aesthetic appeal, which pertains more to design rather than usability. Immediate comprehension of content may not always be feasible due to varying levels of literacy and familiarity with the subject matter, so an expectation for instant understanding does not align with the goals of accessibility. Similarly, search engine optimization is focused on improving visibility and ranking in search results, which does not directly pertain to making content understandable for users.