Real-time text (RTT) is text transmitted instantly as it is typed or created. Recipients can immediately read the message while it is being written, without waiting.

Real-time text is used for conversational text, in collaboration, and in live captioning. Technologies include TDD/TTY devices for the deaf, live captioning for TV, a feature enhancement in instant messaging, captioning for telephony/video conferencing, telecommunications relay services including ip-relay, transcription services including Remote CART, TypeWell, collaborative text editing, streaming text applications, next-generation 9-1-1/1-1-2 emergency service. Obsolete TDD/TTY devices are being replaced by more modern real-time text technologies, including ip-relay and instant messaging.

Real-time text is also possible over any XMPP compatible chat networks, including those used by Apple iChat, Cisco WebEx, and Google Talk, by using appropriate software that has a real-time text feature. When present in IM programs, the real-time text feature can be turned on/off, just like other chat features such as audio. Real-time text programs date at least to the 1970s, with the talk program on the DEC PDP-11, which remains in use on Unix systems.

Total Conversation defines the simultaneous use of audio, video and real-time text. An instant messaging program that can enable all three features simultaneously, would be compliant. Real time text is an important part of it.