Screen Reader Support
A screen reader is software for people with a visual or reading impairment that outputs on-screen content as synthetic speech or on a braille display, and it depends on semantically correct HTML and ARIA markup to do so.
In practice
A short test of your own with a free screen reader – NVDA on Windows or VoiceOver on the Mac, for example – often reveals surprisingly quickly which forms, menus or image descriptions do not work in practice, even though they look perfectly ordinary on screen.