The Application Layer of the TCP/IP model defines application layer transport services (not to be confused with the transport layer) such as the Hyper Text Transfer Protocol (HTTP), File Transport Protocol (FTP) and Domain Name System (DNS). It is used to abstract the details of transportation services of IP hosts.

The TCP/IP and OSI network models both define the Application layer as the highest layer in the stack. However, the Presentation (L6) and Session layer (L5) of the OSI model are combined into the Application Layer of the TCP/IP model.