Wikipedia: RTP

RTP is the "Real-time Transport Protocol", developed by the IETF and published as [RFC 1889]. RTP was also published by the ITU-T as H.225.0.

RTP defines a standardized packet format for delivering audio and video over the Internet. It was originally designed as a multicast protocol, but has since been applied in many unicast? applications. It's frequently used in streaming media solutions (in conjunction with RTSP) as well as videoconferencing? solutions (in conjunction with H.323? or SIP).