Purpose of propaganda
Soviet Propaganda Poster during the Great Patriotic War. The text reads "Red Army Soldier - SAVE US!"
The aim of propaganda is to influence people's opinions or behaviors actively, rather than merely to communicate the facts about something.
Propaganda might be used to garner either support or disapproval of a certain position, rather than to simply present the position; or to try to convince people to buy something, rather than to simply let them know there is a particular item on the market. What separates propaganda from "normal" communication is the ways by which the message attempts to shape opinion or behavior, which are often subtle and insidious. For example, propaganda is often presented in a way that attempts to deliberately evoke a strong emotion, especially by suggesting illogical (or non-intuitive) relationships between concepts or objects (for instance between a “good” car and a pretty woman).
The method of propaganda is essential to the word's meaning as well. A message does not have to be untrue to qualify as propaganda. In fact, the message in modern propaganda is often not blatantly untrue. But even if the message conveys only "true" information, it will generally contain partisan bias and fail to present a complete and balanced consideration of the issue. Another common characteristic of propaganda is its quantity. For example, a propagandist may seek to influence opinion by attempting to have a message heard in as many places as possible, and as often as possible. The intention of this approach is to reinforce an idea through repetition and exclude or "drown out" any alternative ideas.
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 minds 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.