Which layer of the OSI model is responsible for establishing, maintaining, and terminating a connection between applications?

The Session Layer of the OSI model plays a critical role in managing the connections between applications. It is specifically designed to establish, maintain, and terminate sessions, ensuring that two applications can communicate as intended. This layer manages the dialogue between the applications, organizing how data is exchanged in a way that can handle continuous data streams and multiple exchanges without losing track of the context. By providing services like synchronization, dialogue control, and token management, the Session Layer enables efficient communication and allows applications to communicate effectively even over long periods or intermittently.

The other layers, while important in their respective roles, do not handle session management in the same way. The Transport Layer is concerned with end-to-end communication and reliability of data delivery, while the Network Layer focuses on routing packets through the network, and the Application Layer is responsible for interactions that occur at the user interface level, essentially serving as the window through which users access the network services. Each layer has a unique purpose, but it is the Session Layer that specifically addresses the needs related to establishing and managing sessions between applications.