As with so much else in English, "�tiquette" is a French word - its original (and still current) meaning in French is "label"; I am unsure of how it came ot mean "polite behaviour" in both English and French. Etiquette arises from a generally uncodified consensus within a society as to what does and does not constitue acceptable behaviour. It can vary hugely in intensity and application, from the relative informality of Northern and Western Europe, South Africa, Australasia, Canada, and the USA, to the relatively constrained behaviour in the Indian sub-continent plus Afghanistan and Iran (with constitute a socio-linguistic continuum of sorts), the Islamic lands, the people of the Congo and Niger valleys... the list is endless. "Protocol" comes from a Greek word, "prot�kollon" (a neuter noun, stress on the first "o" - the first is an "omega", and the other two are "omicrons"). It has two meanings in Greek: (a) a register of correspondence, and (b) behaviour current at court and in diplomatic circles. Thus, it could be argued that protocol is a special aspect of etiquette.