It's not an easy problem, as the war being waged for many years now I think demonstrates. A too simple definition will have too many exceptions: a newspaper tha

It's not an easy problem, as the war being waged for many years now I think demonstrates. A too simple definition will have too many exceptions: a newspaper that includes an article from another reputable news site, ad? A paid piece extolling the virtues of product X, posing as a fake article, not an ad?