OSI Layer Model

OSI Reference Model in short called OSI Model or Layer Model is a conceptual or logical model that providing understanding of communication between devices and networks. Its a basic designed and all protocol designed upto now to keep this design in mind. In era of 70's two organization OSI and CCIT started work differently started a project, each developed a document that define similar network model.In 1983 two documents one from ISO and other from CCIT merged to form a standard model called Open system interconnection. It was released in 1984 by both organization ISO and CCIT. Following are seven layer of OSI Model

• Application Layer
• Presentation Layer
• Session Layer
• Transport Layer
• Network Layer
• Data Link Layer
• Physical Layer

Every layer deals with its own responsibility,the model also called "Bottom Up" model. Because every layer serve the upper layer. The upper 3 layer deals with software and next 4 deals with software and hardware. Before we explain seven layers few things in short need to understand.
Authority: In every network always a authority that makes work happen as required, so the main authority is "Protocols". Protocols help each OSI layer to perform its responsibility to run network.
Protocol: In simple word Protocol mean rules and regulation. In network such rules and regulation that actually helps to perform communication is called network protocols. Protocols have responsibility to provide communication. ISP (Internet Service Provider) is the best example of protocol.
Default Gateway: A device thorough which network traffic comes in and out to internet, that path is  is called default gateway.
"WWW." is responsible for website you required."FTP" is responsible for transferring pages to your devices."HTTP" is responsible for loading pages to your browser.