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The OSI Model

The outside of an elegant building.  Source: Microsoft.

The International Organization for Standardization (ISO) is an organization that is responsible for the standardizing of methods by which computers communicate with each other. In 1984 the ISO devised their model for network communication. This model is called the Open Systems Interconnection (OSI) reference model or more commonly the OSI model.

The OSI model divides network communications into seven layers. Each layer is responsible for carrying out specific functions when transmitting data on the network. Each layer of this 7 layer structure has a definite function.

These layers can be recalled using the following acronyms:

All People Seem To Need Data Processing. (Layers 7 down to 1)

People Do Not Throw Sausage Pizza Away (Layers 1 up to 7)

Each of the letters represents a different layer (note that the order of these layers is critical)

Next: Layers of the OSI Model