Computer Science Logo

What is OSI Model and OSI layers [Explained]

What is OSI Model

OSI Stands for Open System Interconnection. This is a reference model which means this is only for understanding purpose and does not exists in the real world. The OSI Model is only to understand how the TCP/IP or in simple world how the internet works. OSI Reference Model has 7 layers which are mentioned below.

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.

You can also visit the home page of our website to see the trending topics or you can discover more articles. All the images are taken from you can download free high definition images for free.

Table of Contents

Share This Post With Your Friends

Share on facebook
Share on twitter
Share on linkedin
Share on reddit
Share on telegram
Share on whatsapp
Share on email
Share on print
Share on tumblr
Share on pinterest
Share on vk
Share on odnoklassniki
Aftab Ahmed

Aftab Ahmed

I am a student of Computer science and I explain the topics of Computer Science in a way that everyone can understand. My job is to make the topics simple for everyone so that they don't have to read through long and difficult books in order to understand the concepts.

Symmetric and Asymmetric Cryptography explained

What is Symmetric and Asymmetric cryptography?

If you decided to not read the above articles for some reason let’s have a sneak peek into what those words basically mean. The word Cryptography has been derived from the Greek word “kryptós” which means “Hidden or Secret”. Before we get further into it let’s discuss why do we even need encryption in the first place?

Read More »
TCP Flags - TCP Communication methods

TCP Flags – TCP Communication methods

TCP is a way of Secure communication in which the network makes sure that everything that has been sent has reached its destination without any loss in the packets. It uses the Flags to communicate with the receiver and ask for a confirmation on each packet it sends. It also uses the flags to establish the connection with the receiver so that it can know that receiver is able and willing to receive the data. Here is a detailed description of the most common TCP Flags and their function.

Read More »

6 thoughts on “What is OSI Model and OSI layers [Explained]”

  1. Thank you for the auspicious writeup. It in reality was a amusement
    account it. Glance complicated to far delivered agreeable from you!

    By the way, how could we be in contact?

  2. Hey there would you mind stating which blog platform you’re using?

    I’m going to start my own blog in the near future but I’m having
    a tough time making a decision between BlogEngine/Wordpress/B2evolution and Drupal.
    The reason I ask is because your design and style
    seems different then most blogs and I’m looking for something unique.
    P.S Sorry for getting off-topic but I had to ask!

  3. Hello there, just became aware of your blog through Google, and found that it is truly informative.
    I am going to watch out for brussels. I’ll appreciate if
    you continue this in future. Many people will
    be benefited from your writing. Cheers!

Leave a Comment

Your email address will not be published.