The OSI model was developed starting in the late 1970s to support the emergence of the diverse computer networking methods that were competing for application in the large national networking efforts in the world. Classes of functionality are realized in software by standardized communication protocols.
Each intermediate layer serves a class of functionality to the layer above it and is served by the layer below it. The model partitions the flow of data in a communication system into seven abstraction layers, from the physical implementation of transmitting bits across a communications medium to the highest-level representation of data of a distributed application. Its goal is the interoperability of diverse communication systems with standard communication protocols.
The Open Systems Interconnection model ( OSI model) is a conceptual model that characterises and standardises the communication functions of a telecommunication or computing system without regard to its underlying internal structure and technology.
