The widely-used number associated with the Holocaust is 6 million. 6 million Jews were murdered by the Nazis. However, counting all those who were persecuted, the figure would be between 11 million and 17 million.
The definition of Holocaust (in terms of Nazi Germany) is: "The mass murder of Jews under the German Nazi regime during the period 1941–45." Personally, I agree with those who say that the Holocaust should include everyone the Nazis persecuted.
Ps. Sorry for such a somber/depressing topic!