OSI Model

Open System Interconnection Model:

Physical Layer:
it performs all the functions related for establishing a physical home of communication
like hardware specification,topology,encoding n signaling etc.

Data Link Layer:
it provides the reliable transmission of a packet using physical layer services.Means it links the data to physical layer.
it is also dived into two parts Medium acces layer and Logical Link layer

Network Layer:
It provides the way of transmission of packets(routing) n also congestion control n internetworking.

Transport Layer:
it performs the transmission of packets like using Multiplexing/demultiplexing,fregmentation,error control,flow control etc.

Session Layer:
It is responsible for all the authorization security by creating sessions.

Presentation Layer:
It tells us that in which syntax n semantics  the informations should be transmitted n also include compression,encryption.

Application Layer:
Application layer refers to Application Protocol.The choice of which specific protocol n thier associated functions r to be used at the application lavel is up to the individual user HTTP,FTP etc.