The Open Systems Interconnection project at ISO is a reference model (unlike TCP/IP which is a protocol model).
The application layer contains the protocols for process to process communication.
Provides common representations of the data transferred between layer 7 services.
Like layer 6 does to 7, it provides services to the presentation layer.
It defines the services for transport data between end devices.
Provides services to exchange data over network between identified end devices.
Provides methods for exchanging data frames over a shared media.
Describes the hardware, and means of physical connections used for transmission of data.