The Session layer is responsible for setting up, managing, and then tearing down sessions between Presentation layer entities. This layer also provides dialog control between devices, or nodes. It coordinates communication between systems and serves to organize their communication by offering three different modes: simplex , half duplex , and full duplex . To sum up, the Session layer basically keeps applications’ data separate from other applications’ data. For a good example, the Session layer allows multiple web browser sessions on your desktop at the same time.