The Holocaust was the systematic persecution and genocide by Nazi Germany and its collaborators of the Jews and other minority groups throughout World War Two (1939-1945). These other groups included Romany gypsies, people with physical and mental disabilities, communists, homosexuals and other nationalities considered 'racially inferior' by the Nazis, including Poles, Serbs and Russians. The Jews were the biggest victims, murdered under the Nazi's 'Final Solution of the Jewish Question'. The usual estimate for the number of Jews killed in the Holocaust is six million. Up to two million non-Jewish Poles are also thought to have been killed and up to an estimated three million from the other minority groups targeted in the Holocaust.

The Holocaust was systematically conducted in most areas of Nazi-occupied territory. Many were killed in specific death camps between 1942 and 1945, usually by being poisoned in gas chambers. The largest death camp was Auschwitz-Birkenau in Poland, responsible for the deaths of an estimated 1.6 million Jews. Prior to the death camps, killings were mainly by shootings. The Holocaust, authorised by Hitler himself, is believed to have been centrally planned by senior Nazi officials at the Wannsee conference held near Berlin on January 20 1942.