The RTCSessionDescription interface describes one end of a connection—or potential connection—and how it’s
configured. Each RTCSessionDescription consists of a description type indicating which part of the offer/answer
negotiation process it describes and of the SDP descriptor of the session.
The read-only property RTCPeerConnection.iceGatheringState returns a string that describes the connection’s ICE
gathering state. This lets you detect, for example, when collection of ICE candidates has finished.
The read-only connectionState property of the RTCPeerConnection interface indicates the current state of the peer
connection by returning one of the following string values: new, connecting, connected, disconnected, failed, or
closed.