A protocol is a set of rules that governs the communications between computers on a network. These rules include guidelines that regulate the following characteristics of a network: access method, allowed physical topologies, types of cabling, and speed of data transfer. The most common network protocols are. Ethernet, Local Talk,Token Ring,FDDI,ATM.
Network standards are also ground rules that are set by commissions so that hardware is compatible among similar computers and assures interoperability. This is done to ensure that backwards compatibility and compatibility from vendor to vendor. It is necessary to have standards because if each company had its own protocol standards and didn't allow it to talk with other protocols there would be a lack of communication from different machines and would result in one company being hugely successful and the other running out of business due to lack of being able to communicate with other machines. So this is why its necessary to have network standards and protocols because they are what allow different computers from different companies running different software to communicate with each-other making networking possible.