What is Myth? -- an introductory glance at Alan Dundes' "Sacred Narrative: Readings in the Theory of Myth"
A myth is a ‘sacred narrative’ that attempts to explain how the world and man came to be in their present form.
There are relatively few examples of 'creation ex nihilo' in traditional mythology. Typically, a creator takes some already existing matter and shapes it into man. Rarely is an explanation offered for the origin of the matter to be shaped. Even modern scientific theories, if their initial premises are questioned critically, cannot easily account for the ultimate origins of matter and the universe.
Untrue statements are not myths, nor are myths untrue statements. It is only the modern usage of the word myth as ‘error’ or ‘fallacy’ that has led to the notion of myth as something negative (although it is true that Plato opposed myths because he felt they led men astray).
Myths are traditionally remembered narratives of actual historical cosmological events. If one keeps this in mind, then one can easily eliminate most if not all the books and articles employing myth in their titles, which use the word myth loosely to refer to anything from an obviously erroneous statement to an alleged ‘archetypal’ theme underlying a modern novel or poem.
That myths are ‘sacred’ distinguishes myth from other forms of 'folk narrative.' That myths are ‘sacred’ means that all forms of religion incorporate myths of some kind.
The study of myth is is an international and interdisciplinary venture. Carefully assembling different versions of the same myth along guidelines of clear-cut cross-cultural correlations, we may eventually arrive at a historical reconstruction of the cosmological events that originally inspired our beliefs about our world and ourselves.