•International Standards Organization (ISO) develop Open Systems Interconnection (OSI) Reference Model as the standard for networks.
•The protocol is a well-known set of rules and formats used for communication.
•The protocols developed as part of the OSI model never widely used. However, the underlying model has proved to be quite useful for understanding computer networks.
•With connection-oriented protocols, the sender and receiver must establish connection before communication.
Example: telephone
•With connectionless protocols, no setup in advance is needed.
Example: postal service
•In the OSI model, communication is divided up into seven levels of layers.
