Open Systems Interconnection (OSI) networking reference mode
A reference model is a conceptual framework for understanding relationships.
The OSI model uses layers to help give a visual description of what is going on with a particular networking system ( Communication between computer A and B).
This can help network managers narrow down problems (Is it a physical issue or something with the application?), as well as computer programmers (when developing an application, which other layers does it need to work with?).
Tech vendors selling new products will often refer to the OSI model to help customers understand which layer their products work with or whether it works “across the stack”.