functions of the application layer of the osi model
Application layer In the OSI model, the definition of the application layer is narrower in scope. The OSI model defines the application layer as the user interface responsible for displaying received information to the user. In contrast, the Internet Protocol Suite does not concern itself with such detail. OSI also explicitly distinguishes additional functionality below the application layer, but above the transport layer at two additional levels: the session layer, and the presentation layer. OSI specifies a strict modular separation of functionality at these layers and provides protocol implementations for each layer.
Computer program Computer programs may be categorized along functional lines. The main functional categories are application software and system software. System software includes the operating system which couples computer hardware with application software.[22] The purpose of the operating system is to provide an environment in which application software executes in a convenient and efficient manner.[22] In addition to the operating system, system software includes embedded programs, boot programs, and micro programs. Application software designed for end users have a user interface. Application software not designed for the end user includes middleware, which couples one application with another. Application software also includes utility programs. The distinction between system software and application software is under debate.