The Open Systems Interconnection Model (short:OSI model) was designed by the International Organization for Standardization (IOS) as a reference model for open communication through various technical systems. This makes sense when you think about the early days of the internet: at the end of the 1970s, all of the leading manufacturers for network technology were dealing with the problems brought on by proprietary network infrastructures. Following this, devices from ‘manufacturer A’ could only be used within that same company’s own network, as these products were not compatible with the networks of its competitors. At the time, there simply was no incentive in place to encourage engineers to design their products and systems with those of rival companies in mind. The dawn of the internet completely changed this paradigm, since common standards were needed in order to facilitate shared communication and network access.
The OSI model is the result of such standardization attempts and, as conceptual framework, offers a design basis for creating communication standards independently of manufacturers. In order to achieve this, the ISO OSI model subdivides the complex process of network communication into seven levels, also referred to as layers. This is where the term, OSI layer model comes from. When communicating between two systems, specific tasks have to be carried out on each layer. Such tasks include communication control, addressing target systems, or translating data packages into physical signals. This only works, however, when all systems involved with communication adhere to certain rules, which are determined in protocols.
The ISO reference model, on the other hand, is not a concrete network standard. Instead, it describes, in abstract form, which processes need to be regulated so that network communication is able to take place.