The Open Systems Interconnection model (OSI model) is a conceptual model that defines the communication functions of a telecommunication or computing system without regard to its underlying internal structure and technology.
The Model conists of seven “Layers.” I think of the Layers as Building Blocks. These Blocks are built from the ground up. So as we can see below, the Physical Layer represents the “Physical” Signal that is sent. The second layer represents the type of networking used, the third layer builds on that by providing routing to other networks and so on.
The building blocks are equally important and dependent on the layer below them. Another way to think about it as a Standardized Networking Ecosystem.
The purpose of the OSI reference model is the foundation 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.
One more thing… I know there are a bunch of mnemonic ways to remember these, but the only true way to remember is to understand.0