The OSI Model we just looked at is just a reference/logical model. It was designed to describe the functions of the communication system by dividing the communication procedure into smaller and simpler components. But when we talk about the TCP/IP model, it was designed and developed by the Department of Defense (DoD) in the 1960s and is based on standard protocols. It stands for Transmission Control Protocol/Internet Protocol. The TCP/IP model is a concise version of the OSI model. It contains four layers, unlike seven layers in the OSI model. The layers are:

1. Process/Application Layer
2. Host-to-Host/Transport Layer
3. Internet Layer
4. Network Access/Link Layer

TCP/IP model

• The TCP/IP model was developed prior to the OSI model.
• The TCP/IP model is not exactly similar to the OSI model.
• The TCP/IP model consists of five layers: the application layer, transport layer, network layer, data link layer, and physical layer.
• The first four layers provide physical standards, network interface, internetworking, and transport functions that correspond to the first four layers of the OSI model, and these four layers are represented in the TCP/IP model by a single layer called the application layer.
• TCP/IP is a hierarchical protocol made up of interactive modules, and each of them provides specific functionality.