The ISO/OSI model describes computer communication services and protocols, without making assumptions concerning:
A model is simply a way of organizing knowledge and provides the common
basis for discussion.
The ISO OSI Reference Model is a layered model - with each layer providing certain services and calling upon the services of other layers.
responsible for managing the communication between the applications
provides common operations on the structure of data being exchanged
Provides the control structure for managing communications
Provides reliable transparent data transfer between end points (there may be more than two end points)
Makes the upper layers independent of the data transmission, switching technologies, and topology of the network
Provides reliable transfer across the physical links
Provides transmission of unstructured bits across the physical medium