Open Systems Interconnection Specification

The Open Systems Interconnection Specification (OSI)- refers to the use of the specifications laid out in the OSI reference model. The specifications include how the seven different protocol layers (often referred to as a protocol stack) communication both intra- layer and inter- layer. The OSI evolved as an international standard as there existed a need to standardise how hardware and software communicate depaite possible differences in architecture used. It is a joint effort between two international standard bodies: the International Organization for Standardization (ISO) and the International Telecommunication Union-Telecommunications Standards Sector (ITU-T).

Each OSI--Protocol Specification operates at a single layer. Each defines the primitive operations and permissible responses required to exchange information between peer processes in communicating systems to carry out all or a subset of the services defined within the OSI--Service Definitions for that layer. There are seven layers in the OSI protocol stack.