In this blog I'll be explaining the OSI model in the most basic way possible, for the same reason I'll refrain from using standard definitions. Let's start!

To begin with, OSI stands for "Open System Interconnection" and it is a theoretical networking model. It was developed by ISO in 1984. It has a 7 layer architecture with each layer having specific functionalities and they work collectively to transmit data globally. The 7 layers are namely Physical, Data Link, Network, Transport, Session, Presentation and Application Layers.

Physical, Data Link and Network Layers are collectively called Hardware Layer while Session, Presentation and Application Layers are collectively called Software Layers. The Transport connects these Hardware and Software Layers.

Actual Working:

The OSI model is implemented both at sending and receiving ends. For the senders side the architecture starts from Application layer down to the Physical layer and just the opposite is followed on the receivers end.

Step 1: While sending any data lets say a text message, you open the application and type the text, this comes under Application layer; protocols like http and https also work in this layer.

Step 2: Next comes the Presentation layer, as the name suggests this layer deals with the format in which the data is sent and received. It also deals with the encryption, decryption and compression of data. Generally encryption is done at senders end.

Step 3: Next comes the Session layer, it is responsible for setting up a session between sender and receiver till all the data is transmitted.

Step 4: Data received from the Session layer is segmented in the Transport layer, protocols like TCP and UDP work in the Transport Layer.

Step 5: Next comes the Network layer, the IP addresses for both the sender and receiver are stored here. The data segments received from the Transport layer are converted to network packets.

Step 6: Next comes the Data Link layer, here the data packets are converted to frames. This layer is responsible for making sure that the data is error free and maintaining data flow.

Step 7: Next comes Physical layer, here the data from data link layer is converted into bits. Networking devices like hubs, receivers etc. are part of this layer. It depends of this layer whether the data will be transferred wirelessly or not.

Next the same procedure is repeated in the exact opposite order at the receiver end and voilà! your data has been transferred!