A mythology or a mythos is a collection of myths, especially one belonging to a particular culture or tradition. In such a context, a myth is a sacred narrative that explains the present state of the world or humanity.  In a broad sense, however, the word can refer to any traditional story. Myths arise as explanation of ritual, allegory, elaborated versions of historical events, establishments of behavioural models, teaching, or for depiction of cultural phenomena. In a modern context, myth can also be formed from the artificial mythoi of fictional works and the works of fantasy writers or urban legend.
The word "myth" comes from the Greek word mythos, "speech". The word underwent a long change of meaning; in the eighth century b.c.e, mythos did not really mean "a fictional tale". By the fifth century b.c.e the word was primarily used to contrast with logos, which also means "speech". Logos later gained connotations of rational speech and writing and mythos came to mean "fiction" or "story". By the Late Middle Ages, French had adopted mythologie from Late Latin; Middle English eventually borrowed this as "mythology".