Perceivability

The quality of information or interface elements being detectable through one or more senses — sight, hearing, or touch. Perceivability is the first principle of WCAG 2.0 and requires that information and user interface components be presentable to users in ways they can perceive. However, perceivability alone does not guarantee accessibility; information that is perceivable may still not be understandable if it is poorly structured, uses unfamiliar terminology, or relies on implicit context. Effective accessibility requires both perceivability and understandability.