Godwin's law

Godwin's law is an Internet adage asserting: "As an online discussion grows longer, the probability of a comparison involving Nazis or Hitler approaches 1."

Promulgated by the American attorney and author Mike Godwin in 1990, Godwin's law originally referred specifically to Usenet newsgroup discussions. He stated that he introduced Godwin's law in 1990 as an experiment in memetics, specifically to address the ubiquity of such comparisons which he believes regrettably trivialize the Holocaust. Later, it was applied to any threaded online discussion, such as Internet forums, chat rooms, and social-media comment threads, as well as to speeches, articles, and other rhetoric where reductio ad Hitlerum occurs.

In 2012, Godwin's law became an entry in the third edition of the Oxford English Dictionary.