What is propaganda, and what is it in WWI and WWII and how did Hitler use it?

The ability of the government to guide and mold public opinion is the essence of propaganda.  In World War I and in World War II, it was used to ensure that public support would be for the governmental aims in fighting the war.  Both sides used it to maintain public zeal and morale.  The fact that both sides used it would prove how much of a lie propaganda actually is:  How can both sides be right in asserting their own valid claims?  This is to say, if both sides are asserting their moral claims and the morally invalid claims of the other, someone has to be lying.  Propaganda is essential to continuing the strength of the state and ensuring that dissent is not heard.  Hitler was fairly effective in utilizing propaganda in his scapegoating of individuals whom he deemed as "enemies of Germany."  Along with Goebbels and other aspects of the Reich Government, he was able to mobilizing public support and zeal for his aims and ensure this was done without a great deal of support.  In providing a template as to how centralized governments do not need to listen to their constituents, Hitler was sadly ahead of his time in his use of propaganda and "spin" in the advancement of his own personal and political agenda.