A screen reader is a software application which, rather than presenting web content visually, converts text into 'synthesised speech' allowing user to alternatively listen to content. In more accurate terms â€“ content displayed in screen is sent to standard output, whether a video monitor is present or not. Interpretations are then synthesised 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 light-duty screen reader since Windows 2000. Apple Inc. Mac OS X, iOS, and tvOS include VoiceOver, a feature-rich screen reader, while Google's Android includes Google Text-to-Speech, also on Android, Samsung devices have Samsung Text-to-Speech. 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.
There are also popular free and open source screen readers, such as the Orca for Unix-like systems and NonVisual Desktop Access for Windows.
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.