Screen Text Readers
Screen readers are software programs that allow blind or visually impaired users to read the text that is displayed on the computer screen with a speech synthesizer. A screen reader is the interface between the computer’s operating system, its applications, and the user. The user sends commands by pressing different combinations of keys on the computer keyboard to instruct the speech synthesizer what to say and to speak automatically when changes occur on the computer screen.
Web accessibility doesn't apply only to those who are completey blind. There are many people who have vision impairments but who can see objects which are magnified. Screen magnifiers are used by partially sighted Web users to increase the size of on-screen elements. The needs of screen magnifier users are often overlooked when implementing Web accessibility policies.