A communication protocol is a set of rules used by devices and systems, components and programs and to enable terminals of a communication system to communicate with each other.
The designation communication protocol simply states that communication takes place between two protocol data units (PDU) on equal protocol layers. The name communication protocol does not indicate on which layer of the OSI reference model the communication takes place. Nor does it indicate which switching technology is used or which security and time-critical aspects are taken into account.
The term communication protocol applies equally to all protocols used in communication: transport protocols, network protocols or application protocols. Communication protocols support connection-related procedures, such as packetization, as well as the transmission and delivery of messages.