3. Definitions

The following terms are used throughout this document:

Agent: An agent is the protocol implementation involved in the offer/answer exchange. There are two agents involved in an offer/answer exchange.
Answer: An SDP message sent by an answerer in response to an offer received from an offerer.
Answerer: An agent which receives a session description from another agent describing aspects of desired media communication, and then responds to that with its own session description.
Media Stream: From RTSP [8], a media stream is a single media instance, e.g., an audio stream or a video stream as well as a single whiteboard or shared application group. In SDP, a media stream is described by an m= line and its associated attributes.
Offer: An SDP message sent by an offerer.
Offerer: An agent which generates a session description in order to create or modify a session.

3. Definitions​