Fundamental principle of politics is Propaganda

Propaganda is a concerted set of messages aimed at influencing the opinions or behaviors of large numbers of people. As opposed to impartially providing information, propaganda in its most basic sense presents information in order to influence its audience. Propaganda often presents facts selectively (thus lying by omission) to encourage a particular synthesis, or gives loaded messages in order to produce an emotional rather than rational response to the information presented. The desired result is a change of the cognitive narrative of the subject in the target audience to further a political agenda.

Propaganda is the deliberate, systematic attempt to shape perceptions, manipulate cognitions, and direct behavior to achieve a response that furthers the desired intent of the propagandist.
—Garth S. Jowett and Victoria O'Donnell, Propaganda and Persuasion
Etymology
The word originates from the Latin name Congregatio de Propaganda Fide ("Congregation for the Spreading of the Faith") of a congregation founded by Pope Gregory XV in 1622. This department of the pontifical administration was charged with the spread of Catholicism and with the regulation of ecclesiastical affairs in mission territory.
The Latin adjective propaganda, which is a form of the gerundive of the verb propago (from pro- "forth" + *pag-, root of pangere "to fasten"), means "that which is to be spread" and does not carry a connotation of information, misleading or otherwise. The modern sense dates from World War I, when the term evolved to be mainly associated with politics.
Types

Propaganda is neutrally defined as a systematic form of purposeful persuasion that attempts to influence the emotions, attitudes, opinions, and actions of specified target audiences for ideological, political or commercial purposes through the controlled transmission of one-sided messages (which may or may not be factual) via mass and direct media channels. A propaganda organization employs propagandists who engage in propagandism—the applied creation and distribution of such forms of persuasion

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Richard Alan Nelson, A Chronology and Glossary of Propaganda in the United States, 1996
Propaganda, in a narrower use of the term, connotes deliberately false or misleading information that supports or furthers a political (but not only) cause or the interests of those with 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 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. 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.
Propaganda is a powerful weapon in war; it is used to dehumanize and create hatred toward a supposed enemy, either internal or external, by creating a false image in the mind. This can be done by using derogatory or racist terms, avoiding some words or by making allegations of enemy atrocities. Most propaganda wars require the home population to feel the enemy has inflicted an injustice, which may be fictitious or may be based on facts. The home population must also decide that the cause of their nation is just.
Propaganda is also one of the methods used in psychological warfare, which may also involve false flag operations. The term propaganda may also refer to false information meant to reinforce the mindsets of people who already believe as the propagandist wishes. The assumption is that, if people believe something false, they will constantly be assailed by doubts. Since these doubts are unpleasant (see cognitive dissonance), people will be eager to have them extinguished, and are therefore receptive to the reassurances of those in power. For this reason propaganda is often addressed to people who are already sympathetic to the agenda. This process of reinforcement uses an individual's predisposition to self-select "agreeable" information sources as a mechanism for maintaining control.
Propaganda can be classified according to the source and nature of the message. White propaganda generally comes from an openly identified source, and is characterized by gentler methods of persuasion, such as standard public relations techniques and one-sided presentation of an argument. Black propaganda is identified as being from one source, but is in fact from another. This is most commonly to disguise the true origins of the propaganda, be it from an enemy country or from an organization with a negative public image. Grey propaganda is propaganda without any identifiable source or author. A major application of grey propaganda is making enemies believe falsehoods using straw arguments: As phase one, to make someone believe "A", one releases as grey propaganda "B", the opposite of "A". In phase two, "B" is discredited using some strawman. The enemy will then assume "A" to be true.

In scale, these different types of propaganda can also be defined by the potential of true and correct information to compete with the propaganda. For example, opposition to white propaganda is often readily found and may slightly discredit the propaganda source. Opposition to grey propaganda, when revealed (often by an inside source), may create some level of public outcry. Opposition to black propaganda is often unavailable and may be dangerous to reveal, because public cognizance of black propaganda tactics and sources would undermine or backfire the very campaign the black propagandist supported.
Propaganda may be administered in insidious ways. For instance, disparaging disinformation about the history of certain groups or foreign countries may be encouraged or tolerated in the educational system. Since few people actually double-check what they learn at school, such disinformation will be repeated by journalists as well as parents, thus reinforcing the idea that the disinformation item is really a "well-known fact", even though no one repeating the myth is able to point to an authoritative source. The disinformation is then recycled in the media and in the educational system, without the need for direct governmental intervention on the media. Such permeating propaganda may be used for political goals: by giving citizens a false impression of the quality or policies of their country, they may be incited to reject certain proposals or certain remarks or ignore the experience of others.