OSI stands for Open System Interconnection.
This method is used to define the method of communication between two devices. OSI model has multiple layers each stacked on one another.
Let's understand the layers one by one.
OSI model layers
These are the seven layers of the OSI model.
Physical layer
Data link layer
Network layer
Transport layer
Session layer
Presentation layer
Application layer
The first four layers ( Application layer, Presentation layer, Session layer, and Transport layer ) are the layers that interact with the software and the bottom three layers ( Network layer, Data Link layer, and Physical layer ) are the layers that interact with the hardware.
Now let's understand the use of each layer.
| Layer | Function | Example | |
| 7 | Application Layer | This is the only layer that interacts with the user. | SMTP |
| 6 | Presentation Layer | This layer is also called as Translation layer. This layer is responsible for encrypting/decrypting data. | JPG, GIF, HTTPS |
| 5 | Session Layer | This layer establishes a connection between two devices/hosts. The period till which this connection is present is called a session. | PPTP |
| 4 | Transport Layer | Responsible for end-to-end communication between two devices, it breaks the data into smaller pieces called segments. | TCP, UDP |
| 3 | Network Layer | Data transfer between networks. If further breaks the segments into small packets and re-assembles them on the sender device. | Routes |
| 2 | Data Link Layer | Somewhat similar to the data link layer, but in this the data is transferred between the same network. | Switches |
| 1 | Physical Layer | Involves the data transfer over to physical layers | NICS, Cables |
Conclusion
So this is the OSI layer explanation in a very simple manner. Do follow me on my socials.
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