System-Class Accessibility

The architectural support built into an operating system to make the entire platform usable by people with disabilities. System-class accessibility encompasses three components: alternative input and output modalities (such as speech synthesis, braille displays, and switch access), APIs that allow applications to expose their content and interactions programmatically, and accessibility services that bridge between alternative inputs/outputs and applications. By implementing accessibility at the system level rather than in individual applications, platforms can support dozens of assistive technologies and hundreds of accessibility settings consistently across all apps. Apple's iOS and macOS, Google's Android, and Microsoft Windows all implement system-class accessibility to varying degrees.