Modern propaganda theory classifies propaganda by attribution — how transparent the source is:

• White Propaganda: The source is clearly and truthfully identified. The audience knows who is speaking. Example: Voice of America broadcasting under the U.S. government's name.
• Grey Propaganda: The source is concealed or not attributed. The message is presented as coming from a neutral or independent party, making it seem more credible than if it came from an identified propaganda agency. Unsigned articles, planted stories in media, and anonymous pamphlets are examples.
• Black Propaganda: The message is falsely attributed to a hostile or enemy source, designed to embarrass that source, undermine its credibility, or provoke it into harmful actions. It is subversive and deceptive by design, typically produced by intelligence agencies. An example is forged letters attributed to enemy commanders.

Harold Lasswell defined propaganda as “the management of collective attitudes by the manipulation of significant symbols.”