That the Holocaust—the systematic mass murder of ~5-6 million Jews—occurred is beyond doubt. If you're curious about the evidence for this, I recommend Michael Shermer's book, ' opening statement in his debate, and this essay by Eric Hunt, a former Holocaust denier who went so far as to kidnap Elie Wiesel, wherein he explains why he stopped denying the Holocaust. The blog Holocaust Controversies is a particularly good source for debunking random claims made by holocaust deniers, because the author is both overwhelmingly knowledgeable and has seemingly infinite patience to track down and rebut claims made by leading revisionists.
The blog Holocaust Controversies is a particularly good source for debunking random claims made by holocaust deniers, because the author is both overwhelmingly knowledgeable and has seemingly infinite patience to track down and rebut claims made by leading revisionists. The evidence is quite overwhelming, so much so that the Nazis hanged at Nuremberg never denied that the Holocaust had taken place.