Open System Interconnection Model

OSI Model or Open System Interconnection Model:

OSI Model defines and is used to understand How data is transferred from one computer to another in a computer network?

In the most basic form, two computers (end-points) connected to each other with LAN Cable (Network Media) and connectors (RJ45) sharing data with the help of NICs forms a network.

But if one computer is based on Microsoft Windows and the other one has MAC OS installed, then how these two computers are going to communicate with each other?

In order to accomplish successful communication b/w computers or networks of different architectures,

7-layered OSI Model or Open System Interconnection Model was introduced by International Organization of standardization.

for Standardization in 1984, containing:

• Application Layer
• Presentation Layer
• Session Layer,
• Transport Layer,
• Network Layer,
• Data Link Layer,
• Physical Layer.

I give you a trick to learn all the OSI model layers.

"All People Seem To Need Data Processing.,,

A-----Application Layer
P-----Presentation Layer
S-----Session Layer
T----Transport Layer
D----Data Link Layer
P-----Physical Layer

Question- Which is first layer os OSI Model?
                  Depends upon the sender and receiver.
                  Sender side 1st layer-Application layer
                  At receiver side- Physical layer 


Note that each layer is a package of protocols (set of rules and conventions).
If I say, Application Layer, then it does not mean that it includes computer applications like Chrome, Firefox etc.

But it includes application layer protocols that are needed to make these applications work correctly in a network or Internet. Let's start with the Top Most Layer in the next tutorial...