The open system interconnection model (OSI), sometimes referred to as the "seven-layer OSI model", is a conceptual and abstract description of the layers through which two or more telecommunication systems or computer networks are connected to each other. The OSI model tries to explain how two data transmission systems are connected based on the types of media in a computer network. The OSI model is not a network architecture, because no service or protocol is defined in it. Rather, it is one of the standard and accepted models that is used to design or describe telecommunication networks.