Yours, Etc.: Origins and Uses of 8 Sign-Offs
The third highest protocol layer (layer 5) in the OSI seven layer model. The session layer uses the transport layer to establish a connection between processes on different hosts. It handles security and creation of the session. It is used by the presentation layer.
Documents: ITU Rec. X.225 (ISO 8327), ITU Rec. X.215 (ISO 8326).