OSI

Intro
The OSI model is defined by seven different layers and is a conceptual model that characterizes and standardizes the communication functions of a telecommunication or computing system without regard to their underlying internal structure and technology.

Layers:
These are just an example of layer 7 and layer 1, there are many others in between.

Advantages:

 * It provides wide variety of choice.
 * It does not depend or rely on a specific computer system.

Disadvantages:

 * Complex.
 * This model is not adapted at all to telecommunication applications on computer.