Short answers, pulled from the story.
For scholars, a myth is a genre of folklore consisting of narratives that play a fundamental role in a society. Whether the narrative is true or false is irrelevant to whether it counts as a myth. Myths are often endorsed by religious and secular authorities and may be natural or supernatural in character.
The word myth comes from Ancient Greek μῦθος, mȳthos, meaning speech, narrative, or fiction. The related term mythología combined mȳthos with the suffix -λογία, meaning study, and Plato used it for fiction or story-telling of any kind. English adopted mythology in the 15th century, first attested in John Lydgate's Troy Book around 1425, while myth itself is first recorded in 1830.
Myths usually feature gods, demigods, or supernatural figures as their main characters, generally have no historical basis, and are set in a remote past. Legends generally feature humans, often leaders of some type. Many exceptions exist, as in the Iliad, Odyssey, and Aeneid.
Euhemerism is the theory that myths are distorted accounts of real historical events, elaborated over many retellings until human figures gain the status of gods. It is named after Euhemerus, around 320 BCE, who argued that Greek gods developed from legends about humans. Herodotus in the 5th century BCE and Prodicus made similar claims.
Nineteenth-century nature mythology was led by Max Müller, who called myth a disease of language, and Edward Burnett Tylor. In the 20th century, Sigmund Freud drew on Classical myth for the Oedipus complex, Jung proposed shared archetypes, Lévi-Strauss developed structuralism, Bronislaw Malinowski stressed social function, and Barthes examined modern myth in his book Mythologies.
The film industry transmits myths to large audiences, with 21st-century films such as Clash of the Titans, Immortals, and Thor using traditional mythology to frame modern plots. Rick Riordan's Percy Jackson and the Olympians series places the Greek deities in a modern-day world. Scholars have also connected fan fiction to myth, with Henry Jenkins describing it as the culture repairing damage where contemporary myths are owned by corporations instead of the folk.