Until 2008, the accepted etymology of the idiom was that red herring were used to train dogs to track scents. This has proved to be a false etymology.
It originated from a news story by English journalist William Cobbett, c. 1805, in which he claimed that as a boy he used a red herring (a cured and salted herring) to mislead hounds following a trail; the story served as an extended metaphor for the London press, which had earned Cobbett's ire by publishing false news accounts regarding Napoleon.
- A smoke-cured and salt-brined herring strong enough to turn the flesh red; a type of kipper.
- (figuratively) A clue or information that is or is intended to be misleading, that diverts attention from a question.