What is OSI Model and Why it Matters: An Ultimate Guide to its 7 Layers and Functions

by | Apr 28, 2021 | Featured, Networking

What is OSI Model

Are you wondering to know What is OSI Model so here is a brief introduction to what it is? The term OSI Stands for “Open System Interconnection”. This is a reference model which means this is only for understanding purpose and does not exist in the real world. The OSI Model is only to understand how the TCP/IP or in a simple world how the internet works. OSI Reference Model has 7 layers which are mentioned below.

What is OSI Model Layers

7. Application Layer

Application Layer is the Final layer for a internet packet to travel. This layer handles the HTTP or HTTPS requests. The example of this layer is the Browser or the app you are using to interact with the internet. In computer networks the layer uses the shared communication protocol and interface. This layer is basically a common language that the application shares to communicate to each other.

6. Presentation Layer

The sixth layer in OSI Model basically presents the data to the Application Layer. It encrypts the data it sends. And decrypts the data it receives.

5. Session Layer

This is the fifth layer in any computer networks which basically handles the sessions within the applications. For instance when you login to Facebook it manages your session. If networks don\’t use this layer, You would have to enter the password upon each click. It basically keeps reminding the browser and the server you are connected to that who are you and you have already been authenticated.

4. Transport Layer

This layer receives the data from Session Layer and break them down in packets. This layer basically tells the server that the user wants a TCP Connection or a UDP Connection. You can read more about TCP and UDP here. This layer also appends the port number from which it is being sent and the the port number it is going to in the header of the packet. This layer is basically responsible for end-to-end communications.

3. Network Layer

This layer it writes the sender\’s IP Address and receiver\’s IP Address onto the packets. The layer handles the IP Addresses. This layer basically communicates with the routers and tells the packets which path to follow. (This will prefer the shortest path). This layer works on Router level which means that if you have a router with internet access. Then this layer will be used.

2. Data-Link Layer

The second layer of networking receives the data from the above layer (Network Layer) and create frames of them. Frame basically contains the MAC Address of the senders Device. This layer add the sender MAC Address into the frames. MAC Address stands for \”Media Access Control Address\”. Routers usually maintains the MAC Addresses. Routers keep the log of what IP Address is assigned to what MAC Address. This is how routers know that who requested the data and to whom the response should be forwarded. This layer works on Switches and does not require the Internet. Means that if you have a local connection and sharing the data then this layer helps you to share.

1. Physical Layer

Physical Layer receives the data from Data-Link Layer and convert them into bits which are later sent to the router.  This Layer contains all the physical things like the Internet Wire or the RJ-45 Port on your computer. This layer is responsible for transferring your packets in the form of digital signals. This layer transfers 1s and 0s to your router through a wire or Wi-Fi Signal.


OSI Model is only for understanding purpose, so that you can know how the internet basically works. All the networks basically uses the TCP/IP Model for communication. You can read more about TCP/IP Model on our website by clicking here. The TCP/IP Model is explained in details with examples on how the computers sends data and how they receives them back? We highly recommend, you should go and read that article too.

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