Wikipedia: Propaganda

Propaganda shares many techniques with advertising. In fact, advertising can be thought of as propaganda that promotes a commercial product; however, propaganda usually has political or nationalist themes. Propaganda can take the form of leaflets, posters, TV, and radio broadcasts and can also extend to any other medium.
Propaganda, in a narrower and more common use of the term, refers to deliberately false or misleading information that supports a political cause or the interests of those in power. The propagandist seeks to change the way people understand an issue or situation for the purpose of changing their actions and expectations in ways that are desirable to the interest group. Propaganda, in this sense, serves as a corollary to censorship in which the same purpose is achieved, not by filling people's heads with approved information, but by preventing people from being confronted with opposing points of view. What sets propaganda apart from other forms of advocacy is the willingness of the propagandist to change people's understanding through deception and confusion rather than persuasion and understanding. The leaders of an organization know the information to be one sided or untrue, but this may not be true for the rank and file members who help to disseminate the propaganda.