Without standards, there would not be a way for two computers to communicate with one another. They allow the hardware and software from different vendors to work together. For Example, standards allow a Gateway machine to communicate with a Dell machine, even though they are made by two different vendors. There are several layers associated with different protocols. Protocols govern communication between different machines but at the same layer. The top layer is called the application layer. This layer allows two application programs that use different servers to communicate with one another. The transport layer allows two hosts to communicate with one another, regardless of the difference in their design. An example would be a desktop PC communicating with a workstation. The internet layer uses directs packets from a source host to the destination host using a different router(s). A route is what is used to describe when a specific message travels between two hosts at the internet layer. Communication along a route is determined by the IP Standard. Packets are used to describe internet layer messages. The data link layer uses switches to govern the movement of messages between a source PC to the computer in which the message is sent to. Frames are used to describe messages at the data link layer. The physical layer transmits bits one at a time between different communication transportation devices such as between two switches, between a switch and a router, etc. A physical link is connection between two devices regardless of their properties. It is possible to find different physical links in the same network. Transmission at the physical layer is done bit-by-bit, rather than using messages.
As described earlier, protocols allow two different machines to communicate at the same layer. Each of the five layers described above have a protocol in which they must use to communicate effectively between one another.