A hoax is deliberately created and widely publicized false information, often for the purpose of gaining some sort of advantage by its creator. Hoaxes differ from fiction media (such as plays, movies and novels) and from magic in that the audience is unaware that it is being deceived.
The reasons for creating hoaxes are diverse and include practical jokes, causing embarrassment, a marketing technique, and gaining political or military advantage. Hoaxes are probably as old as the human species and can be spread via any sort of communication, including word of mouth, newspapers and magazines, chain letters, radio and television, and social media. Some creators of hoaxes intend to maintain them as long as possible, while others intend to unmask them at a later date. Hoaxes differ from frauds in that frauds are a type of hoax usually created for financial gain, such as tax fraud.
Claiming that some established fact is a hoax, in contrast to creating false information, is also a type of hoax, and some have been quite successful, but often very harmful. One major recent example is the claim that was made by some well-known politicians and others in the U.S. that the seriousness of the Covid-19 virus is a hoax and that it is no more dangerous than the flu (influenza). This proved to be false in various ways, including by the large increase in the death rate that resulted from the virus. Another, widely believed and long-standing, hoax of this type is the statement by some politicians that the claim that the earth is undergoing climate change is a hoax.