An Overview of the OSI Model

The OSI model was developed by the ISO in 1979 and updated again in 1984. It is useful for guiding network development, troubleshooting, and instruction efforts. The OSI model is a seven-layer approach to data networking, with each layer encompassing a specific set of tasks or standards that must be met in order for the network to function.

This model consists of seven layers that separate the tasks, services, and protocols into various layers of the stack. The word stack is used to define the layers that are set upon each other. The higher you go in the stack, the closer you are to the application. The opposite also is true; as you travel down the stack, you’re getting closer to the layers that deal with specific network functionality. The layers are usually stated from top down due to how applications communicate: application, presentation, session, transport, network, data link, and physical.