RTMP streaming protocol, Transmission Control Protocol-based technology, was developed by Macromedia for streaming audio, video, and data over the Internet, between a Flash player and a server. Macromedia was purchased by its rival Adobe Inc. on December 3, 2005. RTMP stands for Real-Time Messaging Protocol and it was once the most popular live streaming protocol.
Adobe explains RTMP as follows,
Adobe’s Real-Time Messaging Protocol (RTMP) provides a bidirectional
message multiplex service over a reliable stream transport, such as
TCP [RFC0793], intended to carry parallel streams of video, audio,
and data messages, with associated timing information, between a pair
of communicating peers.