“Holocaust” is a unique term that refers to the attempted genocide of the Jewish people during the Second World War. Though there were many millions of people senselessly killed during the war, the term “Holocaust” only refers to the murder of the Jews.
Hitler’s Nazi Germany had two aims during the war: to conquer Europe and create “living-space” (Lebensraum) for the German, Aryan race; and to eliminate the Jews. Nazi Germany took specific steps throughout the years of WW2 to make both of these aims a reality, by conquering neighbouring countries, and by rounding up the Jews of Europe for the purpose of exterminating them.
To be clear: there were many groups targeted during WW2, and it was not only Jews killed during the war. Homosexuals, trade unionists, communists, blacks, Gypsies, disabled people, and others, were killed in labour, concentration, and death camps, alongside the Jews. But it is the intent that differed. This is where the nuance of the term “Holocaust” comes from.
During WW2, the Nazis carefully calculated where the Jews of Europe lived. They maintained lists of how many Jews lived in each European country, and sought to eliminate those Jews when they arrived in each of those places. But, they also kept count of the Jews living outside of Europe. They had the numbers of Jews living in Canada, the United States, Australia, South America, and even in African countries. Their intent was the global elimination of the Jewish people. This is what the term Holocaust refers to.
At least six million Jews died in the Holocaust. Millions of others died in WW2. Every single soul was a precious life lost, but the Holocaust was a uniquely Jewish tragedy, and to ensure it does not happen again, must be remembered as such.