OSI model

The Open Systems Interconnection Model (OSI Model) is often called the 7-Layer Model because of 7 individual layers. The model is used to describe and define the communication between systems. The use of the OSI model is intended to facilitate communication and to create compatibilities. Within the model, 7 layers have clearly defined tasks. The first 4 layers are transport oriented and the other layers from 5 to 7 are application oriented. The communication between the layers takes place hierarchically with the layer directly below or above it.