Holocaust denial is the claim that the Holocaust did not happen, or was not as bad as most people think it was. Historians agree that during World War II, the Nazis did kill millions of people during the Holocaust, including many people in concentration camps. They agree that there is more proof in writing, pictures, and places about the Holocaust than any other great killing of people. Holocaust deniers usually call themselves "Holocaust revisionists." They say that the Holocaust is a hoax made up by Jewish people working together.