In TCP/IP model application layer is the 5th layer of the series. The function of Application layer is to define the extreme level protocols required for the number of applications running throughout the network. Application layer directly interact with the application soft wares in order to carry out application processes. This layer also provides semantic conversion between associated application processes. Very frequently used application layer protocols are File Transfer protocol (FTP) and Simple Mail Transfer Protocol (SMTP).
The mentioned link will also help you a lot to know the functioning of application layer.
en.wikipedia.org
The mentioned link will also help you a lot to know the functioning of application layer.
en.wikipedia.org
