In common speech, propaganda is information of a biased or misleading nature meant to either rally support for or discredit a particular cause. The term's root comes from the Latin propaganda, or to propagate. Thus one can easily see the inherent character of disseminating propaganda to as many people as possible.
Propaganda is however a very nebulous term, as there is not really an objective way of classifying a piece of information as wilful propaganda (purposely biased and misleading), accidental propaganda (accidentally biased and misleading), or simply news. In essence, what is the difference between news and propaganda? This is why most marxist-leninists reject the use of the term as a pejorative, and consider instead that everything is propaganda and thus while being a loaded term, the word propaganda is not inherently negative.
Essentially, if propaganda is meant to manipulate opinion, how does it differ from "non-propaganda" news and media? If there is such a difference, then it would objectively make sense to differentiate the words. If there is no difference, as marxist-leninists believe, then all media is propaganda and the term is not inherently pejorative, but its perceived nature becomes a tool to readily discredit anything that does not align with corporate or state lines.
Marxist-leninists also use the term differently from liberals, due to the former's philosophy of materialism. Liberals believe ideas come before matter and thus ideas are the driver of change, which leads them to give properties to information that it does not actually possess, such as the idea that support for revolution (e.g. the American Revolution) is won by convincing people of one's ideas and that it is possible to get someone to fight and die for a cause by simply providing the correct arguments or repeating them enough. In the materialist analysis, communists see that change is driven by material conditions and matter is what gives birth to ideas, and as such material conditions will dictate whether someone fights in the revolution or not (their class character, their wealth...)
In fact, the term used to simply refer to information that was meant to be propagated regardless of its nature or intent, as seen with the Ministry of Information in London during the Second World War, which did not shy away from using the word, or with propaganda departments in major corporations -- Public Relations used to be called propaganda, owing mostly to the efforts of Edward Bernays who pioneered the practice.
In this sense propaganda is often linked with brainwashing, a term invented by the CIA to discredit dissident soldiers during the Korean War.
Notable examples of propaganda
- In October 1990, a 15 year old Kuwaiti girl testified before the US Congress about war crimes committed by Iraq, specifically that Iraqi forces savagely attacked a maternity ward. This testimony was then used to justify the US invasion of Iraq the next year. It was found out in 1992 that the girl was actually the daughter of the Kuwaiti ambassador to the United States and her testimony was fabricated by a "public relations" firm for a Kuwaiti interest group.