VoiceXML is an XML format for creating interactive dialogues between a human and a computer. It features speech synthesis, automatic speech recognition, call control and soundfile playback. VoiceXML is part of W3C's Voice Browser Activity. http://www.w3c.org/voice.

The following is an example of a VoiceXML document:

Hello world!

When interpreted by a VoiceXML interpreter this will output "Hello world" with synthesized speech. Two related formats that can be used within VoiceXML are Speech Synthesis Markup Language SSML and Speech Recognition Grammar Specification SRGS