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.
That is what happened with Montag, the protagonist who is a fireman in charge of burning books, and Faber, a retired English professor who recognizes what the loss of books means to society. Let's take a closer look at their relationship in Fahrenheit 451 by Ray Bradbury.