The TCP/IP connection establishes a point-to-point connection between two applications. The extremes of this connection are marked by an IP address, which identifies the workstation by a port number, which makes it possible to have several connections that are connected to independent applications on the same workstation.

Once the connection is established and the protocol can exchange data over it, the underlying TCP/IP protocol takes care of sending this data, divided into packets, from one end of the connection to the other. In particular, the TCP protocol deals with assembling and disassembling the packets, as well as managing the handshaking that guarantees the reliability of the connection, while the IP protocol takes care of transporting the individual packets and the choice of the best routing of the packets along with the network.

This mechanism underlies the robustness of the TCP/IP protocol, which, in turn, represents one of the reasons for the development of the protocol itself in the military sphere (ARPANET).

The various existing standard applications (such as web browsing, file transfer, and email) use standardized application protocols, such as HTTP, FTP, POP3, IMAP, and SMTP.

Each specific client-server application must instead define and apply its own proprietary application protocol. This can involve the exchange of data in blocks of a fixed size (which is the simplest solution).