7 Layers of the OSI model

The 7 Layers of the OSI model OSI (Open Systems Interconnection) is a reference model for how applications communicate over a network.

A reference model is a conceptual framework for understanding relationships. The purpose of the OSI reference model is to guide vendors and developers so the digital communication products and software programs they create can interoperate, and to facilitate a clear framework that describes the functions of a networking or telecommunication system.

Most vendors involved in telecommunications make an attempt to describe their products and services in relation to the OSI model. And although it is useful for guiding discussion and evaluation, OSI is rarely actually implemented as-is. That's because few network products or standard tools keep related functions together in well-defined layers, as is the case in the OSI model. The TCP/IP protocol suite, which defines the internet, does not map cleanly to the OSI model.