A hoax is a deliberate attempt to deceive or trick people into believing or accepting something which the hoaxer (the person or group creating the hoax) knows is false.

It is possible to perpetrate a hoax by making only true statements using unfamiliar wording or context, such as in the Dihydrogen monoxide hoax. Many hoaxes are motivated by a desire to satirize or educate by exposing the credulity of the public and the media or the absurdity of the target. For instance, the hoaxes of James Randi poked fun at believers in the paranormal and alternative medicine. The hoaxes of Alan Abel, Chris Morris, and others satirize people's willingness to believe the media. Political hoaxes are sometimes motivated by the desire to ridicule or besmirch opposing politicians or political institutions, often before elections.

The word hoax is said to have come from the common magic incantation hocus pocus. "Hocus pocus", in turn, is believed to be a distortion of "Hoc est corpus meum" ("This is my body") from the Latin Mass.