Etiquette is the code that governs the expectations of social behavior and the conventional norm. Etiquette is an unwritten code, which evolves from written rules, for the Greek equivalent of "etiquette" is protocol, the written formula for ceremonial. It usually reflects a theory of conduct that society or tradition has invested heavily in. Like "culture", it is a word that has gradually grown plural, especially in a multi-ethnic society with many clashing expectations. Thus, it is now possible to refer to "an etiquette" or "a culture", realizing that these may not be universal. Etiquette fundamentally prescribes and restricts the ways in which people interact with each other, and show their respect for other people by conforming to the norms of society. As prehistoric people began to interact with one another, they learned to behave in ways that made life easier and more pleasant. Manners had a practical purpose. Then early civilizations developed rules for proper social conduct. Etiquette is dependent on culture; what is excellent etiquette in one society may shock in another. Etiquette evolves within culture.