The Open Systems Interconnection (OSI) model is a set of seven layers that describe the stages that data must go through to travel from one device to another over a network. I am going to describe how the online game, World of Warcraft, uses the OSI model to operate. World of Warcraft is a massively multiplayer online role-playing game (MMORPG). You play the role of a unique character in a persistent online world shared by thousands of other players. Your character progresses and gets stronger as you gain experience, new skills, and more powerful items and equipment. The first layer of the OSI model is the physical layer. This layer describes the physics of the network including the signaling, cabling, and connectors. In a local area network (LAN), the physical signaling sub layer as part of the physical layer communicates with the second layer of the OSI Model, data link. The data link layer is the basic network language. The Network Interface Controller (NIC) in my computer speaks directly to my router at the local level to connect to a computer network. A sub layer of data link is media access control (MAC). This sub layer gives unique identification and access control for computers on an IP network. The third layer of the OSI model is the network layer, also referred to as the “routing” layer. This layer fragments frames to traverse different networks and transfers data sequences from my IP address to the host destination of World of Warcraft at the IP address 161.58.104.2. The World of Warcraft site uses Transmission Control Protocol (TCP), which is found at layer 4, transport. Transport controls the reliability of the link through flow control, segmentation/ desegmentation, and error control. This is the part of the model that sits right on top of IP to move information from one side of the network to another. Next comes the session layer, which is responsible for the establishing, maintaining, and terminating communication between my computer and the World of Warcraft application. The sixth layer, presentation, is the layer right before all of the information reaches my eyes. It is responsible for character encoding and application encryption. The final layer of the OSI model is the application layer and is the only layer I will actually see. This is the time I will be able to start using the World of Warcraft application. References http://en.wikipedia.org/wiki/OSI_model http://us.battle.net/wow/en/ http://www.youtube.com/watch?v=W438koUR04o&list=WL4C4F206E7FF53E35