Hitler and the Nazi Party used mass communication, like radio, film, and print, to involve the German people in carrying out the Holocaust. To get the job done, Hitler employed a Minister of Propaganda, Joseph Goebbels. Hitler, reproduced in photos, film, and radio broadcasts, becomes a symbol of power and leadership for those who follow him, and a symbol of horror and terror for his targets.
Through the reproduction of his image, his voice, and his symbols – the Swastika and the Nazi flag – Hitler becomes an omnipresent force for everybody in Germany. These are the symbols by which the people are enlisted to support Hitler, and they are backed up by some of the most horrific actions you've heard of. They are, ultimately, symbols of fear, irrational prejudice, and terror.
Today, the swastika, the symbol featured in the Nazi flag, has come to symbolize Hitler and the Holocaust and Nazism, but this wasn't always so. The word "swastika" comes from Sanskrit (an ancient language of India) and means "good fortune" (source). The symbol itself is over five thousand years old. Due to its misuse by Hitler, it will be a long time, if ever, before it can be used effectively to positive ends.