Holocaust denial is a notion that the atrocities committed during ww2 by the Nazis in taking them to concentration camps and exterminating them. There has been debate by so many people and the Nuremberg trials showed first hand film footage of the atrocities.
Holocaust denial also means that there was no concentration camps and certainly no gas chambers. It also suggests the number that perished is too much. It suggests that the holocaust is a big hoax cooked up by Zionists in a huge Jewish conspiracy .
It is sometimes inconceivable to see what man does to man. But as the second world war came to a close. The allied forces discovered the camps and chambers. They took plenty of photos and the supreme commander instructed locals to see the atrocities committed .