The Holocaust

What i think about the holocaust is that is was a horrible thing to segregate a group of  people that didn't do anything. What made this happen? Why did this happen? If there wasn't a holocaust we wouldn't know how to not do this and correct are selves. If this wouldn't of happened what would the world be like? Would we be in a holocaust in the world today? If we treat everyone the same I don't think that this would happen again.