OSI layer

OSI(Open System Interconnection) is the communication protocol which is an ISO standard for worldwide communications in the network across different equipmetnts and application for different vendors. It consist of seven layers and most of the new networking models that are designed are based on the OSI Layer. The seven layers are as follows:-
Physical: it is the physical medium in which actual data are being transferred as electrical signals eg are coaxial cables twisted pair cables etc.
Data link: It defines the format of the data in the network, it communicates with the host with the ethernet address which is the 48 bit Mac address.
Network:It uses internet protocol which is responsible for tracking the routes from source to destination.
Transport:it divides the user buffer into network buffer sized datagrams and enforces desire transmission control. there are two transmission protocols in transport layer connection oriented (TCP) and connectionless (UDP).
Session:this layer describes the format of the data sent in a network.
Presentation:it translates the local representation of the data sent into the network to its canaonical for and vice versa
Application: it provides the user interface for eg: ftp,http,telnet, mail etc..