Software on a computer that reads the content of the page to a user. If a website is WCAG compliant people who use screen readers will have access to that web content.
A screen reader is a software application which analyzes the user interface and the associated content from an operating system or an application, such as a web browser, and provides its output via the text-to-speech synthesizer or a refreshable Braille display. In more accurate terms – the content and textual representation of the user interface is sent to standard output, whether a video monitor is present or not. Interpretations are then synthesized to the user with text-to-speech, sound icons, or a Braille output device. Screen readers are a form of assistive technology (AT) which are essential to people who are blind, as well as useful to people who are visually impaired, illiterate, or have a learning disability.
Microsoft Windows operating systems have included the Microsoft Narrator screen reader since Windows 2000. Apple Inc.'s macOS, iOS, and tvOS include VoiceOver, a feature-rich screen reader, while Google's Android provided Talkback screen reader since 2009. Similarly, Android-based devices from Amazon provide VoiceView screen reader. The console-based Oralux Linux distribution ships with three console screen-reading environments: Emacspeak, Yasr, and Speakup. BlackBerry 10 devices such as the BlackBerry Z30 include a built-in screen reader. There is also a free screen reader application for older less powerful BlackBerry (BBOS7 and earlier) devices.
The most widely used screen readers are separate commercial products: JAWS from Freedom Scientific, Window-Eyes from GW Micro, Dolphin Supernova by Dolphin, System Access from Serotek, and ZoomText Magnifier/Reader from AiSquared are prominent examples in the English-speaking market. The opensource screen reader NVDA is gaining popularity.