When we talk about computer networks and how computers operate in networks, things do not remain as simple as it seems to be. Here numerous protocols work in tandem for the sake of data integrity during the course of data transfer. To make things worse there are a lot of vendors in the market who provide and produce great number of network hardware and push us to use them. Therefore to provide a solution and to make all these devices communicate in 1984, The International Organization for Standardization (ISO) developed the Open Systems Interconnections (OSI) reference model. Basically it described how information is transferred from one networking component to another, from the point when a user enters information using a mouse or a keyboard to when that information is converted to electrical or light signals transferred along a piece of wire or radio waves through the air and vice versa. So we can say, OSI reference model provides a foundation to use when you are considering what happens between the network components when they talk with each other.
ISO developed a seven layer model which allowed vendors and network administrators to understand a stable data transfer and also provided guidelines for implementing new networking standards. Table-1 below briefly describes these layers, their associated services and protocols supported. Layer | Function | Service Description | 7 | Application | The Application layer provides an interface between the communication software and any other application that needs to communicate outside the computer on which the application resides. This layer represents the services that directly support applications such as software for file transfers, database access, and electronic mail. | 6 | Presentation | The Presentation layer translates data from the