Network Services
Many Application layer components are network services. In earlier hours you might have read that a layer of the protocol system provides services for other layers of the system. In many cases, these services are a well-defined, integral part of the protocol system. In the case of the Application layer, the services are not all required for the operation of the protocol software and are more likely provided for the direct benefit of a user or to link the network with the local operating system.
It is fair to say that the lower layers of the protocol stack relate to the mechanics of the communication process and are not especially relevant to the everyday user. The Application layer, on the other hand, hosts the great variety ...
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