The word "protocol" is a Latin and it means: the system of diplomatic and military ceremonies. Such definition requires that we make clear the meaning of ceremony and that of diplomacy. Diplomacy means the art of negotiation between countries, and it also means tactfulness and the good procedure, which are two elements of those related to the art of negotiation, which we will describe later.
As for ceremony, it is the procedure or the way of act and living with the others. Or we can say: rules and laws commonly adopted in dealing among individuals and nations.