Open Systems Interconnection (OSI) is a set of internationally accepted and openly developed standards by which open systems should communicate with each other.

The OSI architecture defines the communications process as a set of seven layers, with specific functions isolated to and associated with each layer.

OSI Layer is meant for Networking manufacturers and developers to provide them a standard based on which they can make their products.

All OSI Layers are independent from each other, which makes introducing changes easier as no other layers are effected.

Advantages of using the OSI layered model :

• Allows various types of network hardware and software to communicate.
• Allows multiple-vendor development through standardization of network components.

The Seven Layers of OSI

Application Layer
The seventh , or highest, layer in the International Organization for Standardization’s Open Systems Interconnection (ISO/OSI) model  that manages the communication between application processes.This layer handles issues like network transparency, resource allocation, and problem partitioning.

Presentation Layer
The sixth of seven layers in the OSI model concerned with protocols for network security, file transfers, and format functions.It is mainly responsible for how the data is to be presented to the Application Layer.

Session Layer
The fifth of seven layers of the ISO/OSI model concerned with network management functions including passwords and network monitoring and reporting.It coordinates communication between systems, and serves to organize their communication by offering three different modes: simplex, half duplex, and full duplex.

Transport Layer
The fourth of seven layers of the ISO/OSI model.The transport layer defines protocols for message structure, and supervises the validity of the transmission by performing some error checking.Transport Layer never actually transports the data but only prepares for transporting.

Network Layer
The third lowest layer in the OSI seven-layer model,It is the layer which is responsible for routing data across the network.

Datalink Layer
Layer two, the second lowest layer in the OSI seven-layer model.It controls the transfer of information between nodes over the Physical layer.it splits data into frames for sending on the physical layer.

Physical Layer
The lowest level of the OSI reference model.This layer communicates directly with actual   communication
media.