6. a small strip of coloured cloth signifying membership of an order or award of military decoration, prize, or other distinction. 7. a small, usually looped, strip of coloured cloth worn to signify support for a charity or cause: a red AIDS ribbon.
The books burned were Jewish, Marxist, Bolshevik, or other disreputable or non-German books. These included the works of Heinrich Heine, Sigmund Freud, Thomas Mann, Erich Maria Remarque, Albert Einstein, Walter Benjamin, Karl Marx, Jack London and Margaret Sanger.
Fahrenheit 451 is a novel by Ray Bradbury, depicting a world in which books are outlawed, and firemen start fires, not put them out. The main character is Guy Montag, a fireman. The title is quite clever, because at 451 degrees Fahrenheit, paper combusts.