The application layer provides functions for the applications. This layer connects to the lower layers. At this level, data entry and output also takes place. As a service to application programs, this layer ensures that efficient communication with other application programs within a network is possible. The application layer itself is not the application that performs the communication. Rather, it represents a service layer that provides the following services:
One can easily think of the application layer as a highly efficient setup service for an application or an interactive user.