Scam baiting is a form of Internet vigilantism, where the vigilante poses as a potential victim to the scammer in order to waste their time and resources, gather information that will be of use to authorities, and publicly expose the scammer. It is, in essence, a form of social engineering that may have an altruistic motive or may be motivated by malice. It is primarily used to thwart the 419 Nigerian advance-fee scam and can be done either out of a sense of civic duty or as a form of amusement.
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Wikipedia