Six Million jews
The 'Six Million Jews' refers to the claim that this was the exact number of Jews deliberately and willfully murdered in Germany, during WW2, by forces under the command of Adolf Hitler. Mostly in homicidal gas chambers, disguised as shower rooms. But also by a variety of other cruel and sadistic means.
Proponents of the truth of this claim:
passionately point to thousands of witness testimonies, film footage, and remaining architectural evidence.
They maintain that this historical event is so well documented, that it is outrageous to even question it, and an insult to the memories of the victims.
In many countries, they have successfully lobbied for Holocaust denial laws (punishing Holocaust denial, mocking or minimizing). Involving heavy penalties or prison time.
It is true to say that entire libraries have been compiled with these defenses of the 'Six Million Jews'.
Opponents of the truth of this claim:
Claim that many of these testimonies have been proven to be impostors, and liars. It is true that some have confessed to fraud.
They also claim that the Holocaust claims made can be thoroughly debunked on various grounds, to include Physics, Chemistry, Biology, capability of contemporary cremation technology, coke supplies, Allied photo overflights, shallow water tables (rendering burning pits impossible), Population Census results, International Red Cross Documents (ICRC had open access to all Hitler's camps), and the testimony of Jews who were there, stating they never observed any gas chambers, or evidence of genocidal extermination policies. And many, many other reasons.
It is also true to say that entire libraries have been compiled with these passionate dismissals by Revisionist Historians, of the 'Six Million Jews'.