OSI Full Form is Open Systems Interconnection. OSI is a reference and conceptual model that demonstrates how various applications can communicate over a particular network. This conceptual framework characterizes and differentiates communication systems in a network irrespective of their internal structure and varied technology they are based upon. It is generally the model to understand the underlying relationships among various communication systems.
The main purpose of OSI model is to help users to interrelate and interoperate among various communication models so that they can draw a clear comparing line among those communication tools. It helps the application vendors to define and evaluate various specific features of the programmes. This model is based on seven layers that can implement protocols. Physical, data link, network, transport, session, presentation, and application are the seven layers upon which this model is based.
The control of protocol is passed from one layer to the other, from the starting to the end, from the bottom to the top. Thus it also creates a backup hierarchy. This model does not have any role to play in the networking system and process. It is not at all tangible too. This the reason why only two variants of the OSI model (namely OSI-compliant X.400 and X.500) are used widely, but there are no other notable function of OSI.