The Session Layer is the fifth layer that we can find in the OSI model which essentially deals with interhost communications. This layer is responsible for establishing the process to process communication between the host in the network. So this is the layer which establishing and ending the sessions across the network. This layer allows applications on separate computers to share a connection called a session while providing services such as name lookup and security that allow two programs to find each other and establish the communication link.
In the same time it provides for data synchronization, marks the data stream with checkpoints and monitors the receipt of those checkpoints. This layer also controls the dialog between two processes and determines who can transmit and who can receive at what point during the communication. So it can initializes, manages and terminates connections between local and remote applications while providing simplex, full duplex or half duplex communications