The International Standards Organization / Open Systems Interconnection (ISO/OSI) Layers and Characteristics Standard model for network communications enables dissimilar networks to communicate, Defines 7 protocol layers (a.k.a. protocol stack) Each layer on one workstation communicates with its respective layer on another workstation using protocols (i.e. agreed-upon communication formats) “Mapping” each protocol to the model is useful for comparing protocols. Mnemonics: Please Do Not Throw Sausage Pizza Away (bottom to top layer) All People Seem To Need Data Processing (top to bottom layer). Source: STEINER, Kurt, Telecommunications and Network Security, Version 1, May 2002, CISSP Open Study Group (Domain Leader: skottikus), Page 12.